Streptococcus thermophilus strains with improved textural properties

Abstract

The present invention provides Streptococcus thermophilus mutants having improved eating quality characteristics. Additionally, the present invention relates to compositions, such as starter cultures, comprising one or more of these mutants, fermented products made using these mutants, and uses of the mutants and compositions of the present invention.

Description

[Technical field]

[0001] The present invention relates to Streptococcus Thermophilus mutants having improved eating quality characteristics. The invention further relates to compositions, such as starter cultures, comprising one or more of these mutants, fermented products made using these mutants, and uses of the mutants and compositions of the invention. [Background technology]

[0002] The food industry uses a large number of bacteria, especially lactic acid bacteria, to improve the texture of foods. In the dairy industry, lactic acid bacteria are used intensively not only to bring about the acidification of milk (by fermentation), but also to add texture to the products in which they are incorporated.

[0003] Among the lactic acid bacteria used in the food industry, Streptococcus, Lactococcus, Lactobacillus, Leukonostoc, Pediococcus, and Bifidobacterium are the most widely applied. Lactic acid bacteria of the species S. thermophilus are widely used, alone or in combination with other bacteria such as Lactobacillus delbrueckii subsp. bulgaricus, for the production of food, especially fermented foods. They are used in particular in the formulation of ferments used in the production of fermented milk, e.g. yogurt. Some of them play a major role in the development of the texture of fermented products. This characteristic is closely related to the production of extracellular polymeric substances (exopolysaccharides, EPS) secreted by lactic acid bacteria into the surrounding environment.

[0004] It is desirable to obtain fermented milk products with a high texture. For example, the current trend in yogurt production is towards a mild flavor and high texture. Today, this is achieved by the use of cultures that produce a mild flavor and by adding thickeners or proteins to give the desired thickness. Producers of fermented products (such as yogurt producers) would like to be able to produce fermented products such as yogurt with these properties without adding thickeners. This would help them reduce costs and give a cleaner label. One very attractive way to achieve this is to have starter cultures that produce a high level of texture.

[0005] Many strains of S. thermophilus synthesize exopolysaccharides (EPS). These molecules can be produced as capsules tightly associated with the cells or released into the medium as a loose slime (i.e., "ropy" polysaccharides). The presence of exopolysaccharides does not confer a clear advantage to the growth or survival of S. thermophilus in milk, but their in situ production by this species or other dairy lactic acid bacteria typically imparts a desirable "sticky" or viscous texture to fermented milk products. Studies have also shown that exopolysaccharide-producing S. thermophilus can enhance the functional properties of fermented milk products. For further details, see the review by Broadbent et al. (J. Dairy Sci., 2003, 86:407-423).

[0006] To meet the demands of the industry, it has become necessary to provide novel texturing strains of lactic acid bacteria, particularly S. thermophilus, for adding texture to foods. In particular, there is a need for novel texturing strains of S. thermophilus that can be used together with texturing strains of Lactobacillus, such as L. bulgaricus. Summary of the Invention

[0007] The present invention provides novel S. thermophilus strains that have improved properties, particularly with regard to their ability to improve the texture of fermented foods, such as dairy products, e.g. yogurt, as well as dairy analogue products, and that are useful in the today's highly industrialized fermented food production.

[0008] One aspect of the invention relates to (i) an S. thermophilus strain having a mutation in the branched chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene, wherein the mutation is preferably a substitution of Glutamic Acid to Valine at a position corresponding to position 169 of SEQ ID NO: 12. In another aspect, the invention relates to an S. plaque strain having a mutation in the branched chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene, wherein the mutation is preferably a substitution of nucleotide A to nucleotide T at a position corresponding to position 506 of SEQ ID NO: 11.

[0009] In one embodiment of the invention, the S. thermophilus strain has (ii) a mutation in the ABC transporter permease protein gene, wherein the mutation is preferably a leucine to phenylalanine substitution at the position corresponding to position 190 of SEQ ID NO: 4. In a further embodiment, the S. thermophilus strain of the invention has a further mutation in the ABC transporter permease protein gene, wherein the mutation is preferably a nucleotide C to nucleotide T substitution at the position corresponding to position 568 of SEQ ID NO: 3.

[0010] In one embodiment of the invention, the S. thermophilus strain has (iii) a mutation in the peptide deformylase protein gene, wherein the mutation is preferably a substitution of arginine to cysteine ​​at the position corresponding to position 144 of SEQ ID NO: 8. In a further embodiment, the S. thermophilus strain of the invention has a mutation in the peptide deformylase protein gene, wherein the mutation is preferably a substitution of nucleotide C to nucleotide T at the position corresponding to position 430 of SEQ ID NO: 7.

[0011] In one embodiment, the S. thermophilus strain has (i) a mutation in the branched chain amino acid transport ATP binding protein LivG gene. In one embodiment, the S. thermophilus strain has (ii) a mutation in the ABC transporter permease protein gene. In one embodiment, the S. thermophilus strain has (iii) a mutation in the peptide deformylase protein gene. In another embodiment, the S. thermophilus strain has mutations (i) and (ii), i.e., mutations in the branched chain amino acid transport ATP binding protein LivG gene and the ABC transporter permease protein gene; for example, two mutations as described above, such as mutations (i) and (iii) as described above, or mutations (ii) and (iii) as described above. In a preferred embodiment, the S. thermophilus strain has all three mutations (i), (ii) and (iii) as defined above.

[0012] Thus, the present invention relates to (i) an S. thermophilus strain having a valine at the position corresponding to position 169 of SEQ ID NO: 12 and / or a T at the position corresponding to position 506 of SEQ ID NO: 11 (branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) gene). The present invention relates to (ii) an S. thermophilus strain having a phenylalanine at the position corresponding to position 190 of SEQ ID NO: 4 and / or a T at the position corresponding to position 568 of SEQ ID NO: 3 (ABC transporter permease protein gene). The present invention relates to (iii) an S. thermophilus strain having a cysteine ​​at the position corresponding to position 144 of SEQ ID NO: 8 and / or a T at the position corresponding to position 430 of SEQ ID NO: 7 (peptide deformylase protein gene). In a preferred embodiment, the branched chain amino acid transport ATP binding protein LivG (TC 3.A.1.4.1) gene of the S. thermophilus strain of the invention has a T at a position corresponding to position 506 of SEQ ID NO: 11, and / or the branched chain amino acid transport ATP binding protein LivG (TC 3.A.1.4.1) has a valine at a position corresponding to position 169 of SEQ ID NO: 12. In a further preferred embodiment, the ABC transporter permease protein gene of the S. thermophilus strain of the invention has a T at a position corresponding to position 568 of SEQ ID NO: 3, and / or the ABC transporter permease protein has a phenylalanine at a position corresponding to position 190 of SEQ ID NO: 4. In another embodiment, the S. thermophilus strain of the invention has both (i) and (ii) above. In another embodiment, the S. thermophilus strain of the invention has (i) and (iii) above. In a further embodiment, the S. thermophilus strain of the invention has (ii) and (iii) above. In a preferred embodiment, the S. thermophilus strain of the invention has (i), (ii) and (iii) above.

[0013] Preferably the S. thermophilus strain is DSM22933 or a mutant or variant thereof, and preferably the mutant or variant exhibits the same or similar textural properties as DSM22933.

[0014] In one aspect, the invention relates to a composition comprising said S. thermophilus strain.

[0015] In one aspect, the present invention relates to a method for producing a fermented product comprising fermenting a substrate with a S. thermophilus strain or a composition of the present invention.

[0016] In one aspect, the present invention relates to a fermented food product obtainable by a method according to the present invention or comprising a S. thermophilus strain or comprising a composition according to the present invention.

[0017] The present invention also relates to a method for producing an S. thermophilus strain defined according to the invention, wherein the strain is preferably obtained by using the strain DSM 22587 as starting material, i.e. as mother strain.

[0018] The present invention further relates to the use of a S. thermophilus strain of the invention, or a composition according to the invention, for the production of a fermented product, preferably for the production of a fermented milk product.

[0019] Sequence Listing SEQ ID NO: 1 shows the nucleotide sequence of the ABC transporter permease of DSM22587. SEQ ID NO: 2 shows the amino acid sequence of the ABC transporter permease of DSM22587. SEQ ID NO: 3 shows the nucleotide sequence of the permease of the ABC transporter of DSM22933. SEQ ID NO: 4 shows the amino acid sequence of the ABC transporter permease of DSM22933. SEQ ID NO:5 shows the nucleotide sequence of peptide deformylase of DSM22587. SEQ ID NO: 6 shows the amino acid sequence of peptide deformylase of DSM22587. SEQ ID NO: 7 shows the nucleotide sequence of peptide deformylase of DSM22933. SEQ ID NO: 8 shows the amino acid sequence of peptide deformylase of DSM22933. SEQ ID NO: 9 shows the nucleotide sequence of the branched-chain amino acid transport ATP-binding protein LivG of DSM22587. SEQ ID NO: 10 shows the amino acid sequence of the branched-chain amino acid transport ATP-binding protein LivG of DSM22587. SEQ ID NO: 11 shows the nucleotide sequence of the branched-chain amino acid transport ATP-binding protein LivG of DSM22933. SEQ ID NO: 12 shows the amino acid sequence of the branched-chain amino acid transport ATP-binding protein LivG of DSM22933.

[0020] ABC transporter permease DSM22587 SEQ ID NO:1 - 2001 bp DNA sequence

[0021] SEQ ID NO:2-AA sequence, 666 amino acids MFRLTNRLALSNLIKNRKLYYPYTLATILVIAITYIFTSLTLNSHLDDLPRADAIKTVLGLGLGIVALSSGIIVLYANSFVMKNRSKELGLYSVLGLEKRHLFSMILKETMIMGFVTLLLGIGVGALFDKLIYAFLQRLIGESTGLVSTFQVMTIPIVLVIFACIF SFLVLVNGFRLLRLNPLQLTKDGLKGEKKGRFLVIQTFLGLGAMGYGYYLALSVQNPVIAIMSFFLAVLLVILGTYLLFNAGTTVVLQLLKKKKSYYYKPNNMISISNLVFRMKKNAVGLATIAILSSMVLVTLVGAASIYAGKKDYLVSAAPHDYSSVSGNKVDLTS TKKLMDDFLIKTGEQVNEEVAVSYLFFGIKNQETNKLTVFTKNERKVVPKSIVLVFSQETFKQLTGKELNLSSNQIALYTKNKTFKTQKSLSIDGKNYQIHRQLGDFINKKVPNIYKIIVSDYSYLVVPDIKIFESSMKGTSIAQATYVGVNVKDSTHDAKKNLDL LDQIAGEATKQLAGQTTGVPESYFSANSRYDAEGMVNGFVGGTFFISIFLSIIFMLGTVLVIYYKQISEGYEDRERFVILQKIGLDDLQVKQTIRKQVLTIFFLPLIFAFIHLAFAYHMISLIVRIIGVLNPDLMLVVTIIVCGVFFLAYILVFVLTSRSYRRIVSM

[0022] ABC transporter permease DSM22933 SEQ ID NO:3 - DNA sequence, 2001 bp

[0023] SEQ ID NO:4-AA sequence, 666 amino acids MFRLTNRLALSNLIKNRKLYYPYTLATILVIAITYIFTSLTLNSHLDDLPRADAIKTVLGLGLGIVALSSGIIVLYANSFVMKNRSKELGLYSVLGLEKRHLFSMILKETMIMGFVTLLLGIGVGALFDKLIYAFLQRLIGESTGLVSTFQVMTIPIVLVIFACIF SFLVLVNGFRLLRLNPLQLTKDGFKGEKKGRFLVIQTFLGLGAMGYGYYLALSVQNPVIAIMSFFLAVLLVILGTYLLFNAGTTVVLQLLKKKKSYYYKPNNMISISNLVFRMKKNAVGLATIAILSSMVLVTLVGAASIYAGKKDYLVSAAPHDYSVSGNKVDLTS TKKLMDDFLIKTGEQVNEEVAVSYLFFGIKNQETNKLTVFTKNERKVVPKSIVLVFSQETFKQLTGKELNLSSNQIALYTKNKTFKTQKSLSIDGKNYQIHRQLGDFINKKVPNIYKIIVSDYSYLVVPDIKIFESSMKGTSIAQATYVGVNVKDSTHDAKKNLDL LDQIAGEATKQLAGQTTGVPESYFSANSRYDAEGMVNGFVGGTFFISIFLSIIFMLGTVLVIYYKQISEGYEDRERFVILQKIGLDDLQVKQTIRKQVLTIFFLPLIFAFIHLAFAYHMISLIVRIIGVLNPDLMLVVTIIVCGVFFLAYILVFVLTSRSYRRIVSM

[0024] Peptide deformylase DSM22587 SEQ ID NO:5 - DNA sequence, 615bp ATGGATGCTCAAACCAAAATTATTCGCGCCAGCCACATGATTGATATGAACGATATCATACGCGAAGGCAACCCAACCTTGCGTGCTGTCGCTGAAGACGTAACCCTACCACTTTCAGATGAAGATATTATCCTTGGTGAAAAAATGATGCAG TTTCTTCGTAATTCACAGGACCCTGTTATCGCTGAAAAAATGGGACTTCGAGGAGGTGTTGGTCTTGCAGCACCACAATTAGATATTTCAAACGCATTATTGCTGTTCTCGTTCCAAATCCTGAAGACGCTAAGGGGAATCCACCTAAAGAAG CTTATAGCCTTCAAGAAATCATGTATAATCCTAAAGTAGTTGCTCATTCTGTTCAGGAGGCTGCTCTAGGTAACGGTGAAGGATGCCTTTCAGTCGATCGCGACGTTCCTGGATATGTCGTTCGCCATGCTCGTGTTACTATTGAATACTTCAA CAAAGAGGGTGAAAAGAAACGTATTAAACTCCGTGGTTACGACTCAATCGTTGTTCAACATGAAATCGACCATACTAACGGTATCATGTTCTACGACCGTATCAATAAAGACAATCCATTTACTATCAAGGATGGACTCTTGATTATCGAATAA

[0025] SEQ ID NO:6-AA sequence, 204 amino acids MDAQTKIIRASHMIDMNDIIREGNPTLRAVAEDVTLPLSDEDIILGEKMMQFLRNSQDPVIAEKMGLRGGVGLAAPQLDISKRIIAVLVPNPEDAKGNPPKEAYSLQEIMYNPKVVAHSVQEAALGNGEGCLSVDRDVPGYVVRHARVTIEYFNKEGEKKRIKLRGYDSIVVQHEIDHTNGIMFYDRINKDNPFTIKDGLLIIE

[0026] Peptide deformylase DSM22933 SEQ ID NO:7 - DNA sequence, 615bp ATGGATGCTCAAACCAAAATTATTCGCGCCAGCCACATGATTGATATGAACGATATCATACGCGAAGGCAACCCAACCTTGCGTGCTGTCGCTGAAGACGTAACCCTACCACTTTCAGATGAAGATATTATCCTTGGTGAAAAAATGATGCAG TTTCTTCGTAATTCACAGGACCCTGTTATCGCTGAAAAAATGGGACTTCGAGGAGGTGTTGGTCTTGCAGCACCACAATTAGATATTTCAAACGCATTATTGCTGTTCTCGTTCCAAATCCTGAAGACGCTAAGGGGAATCCACCTAAAGAAG CTTATAGCCTTCAAGAAATCATGTATAATCCTAAAGTAGTTGCTCATTCTGTTCAGGAGGCTGCTCTAGGTAACGGTGAAGGATGCCTTTCAGTCGATCGCGACGTTCCTGGATATGTCGTTTGCCATGCTCGTGTTACTATTGAATACTTCAA CAAAGAGGGTGAAAAGAAACGTATTAAACTCCGTGGTTACGACTCAATCGTTGTTCAACATGAAATCGACCATACTAACGGTATCATGTTCTACGACCGTATCAATAAAGACAATCCATTTACTATCAAGGATGGACTCTTGATTATCGAATAA

[0027] SEQ ID NO:8-AA sequence, 204 amino acids MDAQTKIIRASHMIDMNDIIREGNPTLRAVAEDVTLPLSDEDIILGEKMMQFLRNSQDPVIAEKMGLRGGVGLAAPQLDISKRIIAVLVPNPEDAKGNPPKEAYSLQEIMYNPKVVAHSVQEAALGNGEGCLSVDRDVPGYVVCHARVTIEYFNKEGEKKRIKLRGYDSIVVQHEIDHTNGIMFYDRINKDNPFTIKDGLLIIE

[0028] Branched-chain amino acid transport ATP-binding protein LivG, DSM22587 SEQ ID NO:9 - DNA sequence, 765 bp ATGGCACTTCTTGAAGTTAAAAATTTAACTAAAAACTTTGGTGGTTTGACTGCTGTTGGTGATGTTTCAATGGAACTCAATGAAGGTGAGTTGGTTGGGCTAATAGGGCCAAACGGTGCTGGTAAAACAACCTTGTTCAACCTTTTGACTGGTGTCTATGAGCCAAGTGAAGGGACTGTAACGCTTGATGGTATAGTTCTCAACGGTAAAGCACCTTACAAGATTGCGTCACTCGGTTTGTCACGTACTTTCCAAAATATCCGCCTTTTCAAAGACATGACTGTACTTGAAAATGTTCTTGTTGGTTTATCAAATAAGCAACCTTCAAATTTCTTTGCATCTCTTTTGCGCTTGCCTAAGTACTATTCAAGTGAGGAAGAGTTGAAAGACAAAGCTATGAAGCTCTTGGCTATCTTTAACTTGGATGGTGAGGCAGATACGCTTGCGAAAAACTTGGCTTATGGACAACAACGTCACTTGGAGATTGTTCGTGCGCTTGCAACGGAACCTAAAATTCTTTTCCTCGATGAACCAGCTGCTGGTATGAACCCACAAGAAACAGCTGAGTTGACTGCTCGTATTCGTCAAATTCAAAAAGATTTCGGTATTACAATTATCTTGATTGAGCACGATATGAGTTTGGTCATGGATGTCACTGAGCGTATCTATGTTTTAGAATATGGACGCTTGATTGCAGAAGGAACCCCTGATGAAATTAAGAATAACAAGCGTGTTATCGAAGCTTACTTGGGAGGTGAAGCATAA

[0029] Sequence number 10 - AA sequence, 254 amino acids MALLEVKNLTKNFGGLTAVGDVSMELNEGELVGLIGPNGAGKTTLFNLLTGVYEPSEGTVTLDGIVLNGKAPYKIASLGLSRTFQNIRLFKDMTVLENVLVGLSNKQPSNFFASLLRLPKYYSSEEELKDKAMKLAIFNLDGEADTLAKNLAYGQQRHLEIVRALATEPKILFLDEPAAGMNPQETAELTARIRQIQKDFGITIILIEHDMSLVMDVTERIYVLEYGRLIAEGTPDEIKNNKRVIEAYLGGEA

[0030] Branched-chain amino acid transport ATP-binding protein LivG, DSM22933 sequence number 11-DNA sequence、765bp ATGGCACTTCTTGAAGTTAAAAATTTAACTAAAAACTTTGGTGGTTTGACTGCTGTTGGTGATGTTTCAATGGAACTCAATGAAGGTGAGTTGGTTGGGCTAATAGGGCCAAACGGTGCTGGTAAAACAACCTTGTTCAACCTTTTGACTGGTGTCTATGAGCCAAGTGAAGGGACTGTAACGCTTGATGGTATAGTTCTCAACGGTAAAGCACCTTACAAGATTGCGTCACTCGGTTTGTCACGTACTTTCCAAAATATCCGCCTTTTCAAAGACATGACTGTACTTGAAAATGTTCTTGTTGGTTTATCAAATAAGCAACCTTCAAATTTCTTTGCATCTCTTTTGCGCTTGCCTAAGTACTATTCAAGTGAGGAAGAGTTGAAAGACAAAGCTATGAAGCTCTTGGCTATCTTTAACTTGGATGGTGAGGCAGATACGCTTGCGAAAAACTTGGCTTATGGACAACAACGTCACTTGGAGATTGTTCGTGCGCTTGCAACGGTACCTAAAATTCTTTTCCTCGATGAACCAGCTGCTGGTATGAACCCACAAGAAACAGCTGAGTTGACTGCTCGTATTCGTCAAATTCAAAAAGATTTCGGTATTACAATTATCTTGATTGAGCACGATATGAGTTTGGTCATGGATGTCACTGAGCGTATCTATGTTTTAGAATATGGACGCTTGATTGCAGAAGGAACCCCTGATGAAATTAAGAATAACAAGCGTGTTATCGAAGCTTACTTGGGAGGTGAAGCATAA

[0031] Sequence number 12 - AA sequence, 254 amino acids MALLEVKNLTKNFGGLTAVGDVSMELNEGELVGLIGPNGAGKTTLFNLLTGVYEPSEGTVTLDGIVLNGKAPYKIASLGLSRTFQNIRLFKDMTVLENVLVGLSNKQPSNFFASLLRLPKYYSSEEE LKDKAMKLLAIFNLDGEADTLAKNLAYGQQRHLEIVRALATVPKILFLDEPAAGMNPQETAELTARIRQIQKDFGITIILIEHDMSLVMDVTERIYVLEYGRLIAEGTPDEIKNNKRVIEAYLGGEA DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] definition All definitions of relevant terms herein are as would be understood by a person of ordinary skill in the art in the context of the relevant technology herein.

[0033] In the context of this application, the term "milk" is used in its common sense to refer to the fluid produced by the mammary glands of animals (eg, cows, sheep, goats, buffalo, camels, etc.).

[0034] The term "dairy substrate" can be any raw and / or processed dairy material that can be subjected to fermentation according to the method of the present invention. Useful milks thus include, but are not limited to, any milk solution / suspension, such as full or low fat milk, skimmed milk, buttermilk, reconstituted milk powder, condensed milk, dry milk, whey, whey permeate, lactose, mother liquor from lactose crystallization, whey protein concentrate, or cream. Obviously, the dairy substrate may be derived from any mammal, for example substantially pure mammalian milk, or reconstituted milk powder. At least a portion of the proteins in the dairy substrate are preferably proteins naturally occurring in mammalian milk, such as casein or whey protein. However, some of the proteins may be proteins not naturally occurring in milk.

[0035] Prior to fermentation, the dairy substrate may be homogenized and pasteurized according to methods known in the art.

[0036] "Homogenizing" in any of its embodiments, as used in the context of the present invention, means intensive mixing to obtain a soluble suspension or emulsion. If homogenization is performed before fermentation, it may be performed to break down the milk fat into smaller sizes so that it no longer separates from the milk. This can be achieved by forcing the milk at high pressure through small orifices.

[0037] "Pasteurization", in any of its embodiments, as used in the context of the present invention, means the treatment of a milk base to reduce or eliminate the presence of live organisms, such as microorganisms. Pasteurization is preferably achieved by maintaining a specific temperature for a specified time. The specific temperature is usually achieved by heating. The temperature and duration can be selected to kill or inactivate specific bacteria, such as harmful bacteria. A rapid cooling step may follow.

[0038] "Fermentation" in the context of the present invention, in any of its embodiments, means the conversion of carbohydrates into acids or alcohols or a mixture of both by the action of microorganisms (e.g. lactic acid bacteria (LAB)). The fermentation processes used for the production of food products, such as dairy products, are well known and the skilled person knows how to select suitable process conditions such as temperature, oxygen, amount of microorganisms and process time. The fermentation conditions are selected to support the achievement of the present invention, for example to obtain a fermented food product, such as a fermented dairy product, such as a dairy product, preferably, in any of its embodiments, a fermented food product having an improved texture compared to a food product produced by a method not involving the use of the strain of the present invention or the use of the composition of the present invention.

[0039] The terms "fermented milk" and "dairy" are used interchangeably herein. In the context of the present invention in any of its embodiments, the expression "fermented dairy product" refers to a food or feed product, the preparation of which comprises the fermentation of a milk base by lactic acid bacteria. "Fermented dairy product", as used herein, includes products such as, but is not limited to, thermophilic fermented dairy products or mesophilic fermented dairy products. The term "thermophilic fermentation" as used herein refers to fermentation at temperatures above about 35°C, such as from about 35°C to about 45°C. The term "mesophilic fermentation" as used herein refers to fermentation at temperatures from about 22°C to about 35°C.

[0040] In the context of the present invention, in any of its embodiments, the expression "lactic acid bacteria" ("LAB") refers to food-grade bacteria that produce lactic acid as the main metabolic end product of carbohydrate fermentation. These bacteria are related by their common metabolic and physiological characteristics and are gram-positive, low GC, acid-tolerant, non-spore-forming, rod-shaped bacilli or cocci. During the fermentation stage, the consumption of carbohydrates by these bacteria causes the formation of lactic acid, lowering the pH and leading to the formation of protein coagulum. These bacteria are therefore responsible for the acidification of milk and the texture of dairy products. The S. thermophilus strains of the present invention are classified as lactic acid bacteria.

[0041] In the present context, the term "starter culture" is a culture that is a preparation of one or more than 30 bacterial strains (such as lactic acid bacteria strains) to support the fermentation process in the preparation of fermented products such as various foods, feeds and beverages. In the present context, a "yogurt starter culture" is a bacterial culture that contains at least one Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) strain and at least one Streptococcus thermophilus (S. thermophilus) strain. According to this, "yogurt" refers to a fermented milk product obtained by inoculating and fermenting a milk substrate with a composition that contains L. bulgaricus and S. thermophilus strains.

[0042] "Texture" is also an important quality factor for fermented milk products, and consumer acceptance is often closely linked to the textural properties. The texture of fermented milk depends on the extracellular polysaccharide structure, the bacteria used for fermentation, the process parameters, as well as the milk composition. In the context of the present invention, the rheological properties (texture) of fermented milk products, such as viscosity, can be measured as a function of the shear stress of the fermented milk product, as described below. Viscosity can also be measured by a viscosity pipette test, as described in Examples 2 and 3 below. Furthermore, textural properties can also be evaluated with a suction test, as described in Example 4 below.

[0043] A "texturizing strain" in the present specification and claims is a strain that can be spun at a shear rate of 300 s under the conditions described below and illustrated in the Examples herein. -1 The strain preferably produces a fermented milk having a shear stress of preferably more than 40 Pa, such as more than 44 Pa, measured at a shear rate of 300 s. -1 The fermented milk can be defined as having a strong texture in that it produces a fermented milk having a shear stress of 53 Pa or more, as measured by the FTIR method.

[0044] 200 ml of milk (protein 3.6%, fat 1.5% or 3%) was heated at 95°C for 5 min, cooled to the inoculation temperature (43°C), inoculated with 0.02% FD-DVS starter culture containing a lactic acid bacteria strain, allowed to stand at the inoculation temperature (43°C) until the pH reached 4.60, stored at 6°C for 7 days, then gently stirred and incubated at 13°C for 300 s. -1 The shear stress is measured at a shear rate of .

[0045] In the context of the present invention, "shear stress" can be measured by the following method: When the pH of the fermented milk (e.g. mammalian or plant-based milk) reaches about pH 4.60 at the incubation temperature, e.g. 43°C, the fermented milk product is cooled by transferring the container to ice water and optionally stored at 6°C for 7 days. The fermented milk sample is gently stirred manually by a stick equipped with a perforated disc until the sample is homogenous. The rheological properties of the samples are evaluated with a rheometer (Anton Paar Physica Rheometer with ASC, Automatic Sample Changer, Anton Paar® GmbH, Austria) by using a bob cup. The rheometer was set at a constant temperature of 13°C during the measurements. The settings are as follows: -Retention time (to restore some of the original structure) - 5 minutes without applying any physical stress (vibration or rotation) to the sample - Vibration process (to measure the elastic and viscous moduli, G' and G'', respectively, and thus the complex modulus G * (Calculate Constant strain = 0.3%, frequency (f) = [0.5...8] Hz 6 measurement points over 60 seconds (1 every 10 seconds) - Rotational process (to measure the shear stress at 300 1 / s) -Two processes were designed: -Shear rate = [0.3-300]1 / s, and 2) Shear rate = [275-0.3]1 / s.

[0046] Each step included 21 measurement points over 210 seconds (every 10 seconds). The shear stress at 300 1 / s (-1300s) was selected for further analysis as it correlates with the mouth thickness when swallowing the fermented dairy product.

[0047] As used herein, "viscosity pipette test" refers to a method for determining the viscosity of a product by determining the efflux time from a volumetric pipette. A longer efflux time corresponds to a higher viscosity (see also Example 2).

[0048] The curdled milk was prepared from 200 mL of skim milk inoculated with 1% of the bacterial strain to be tested (cultured overnight in skim milk at 37°C) and incubated for 20 hours at 42°C or 37°C. The viscosity of the curdled milk was measured with a 25 mL graduated pipette and the flow time of the curdled milk from the pipette was measured in triplicate. The curdled milk was carefully stirred with a spoon to homogenize it. A 25 mL graduated pipette was then filled and the time it took for the pipette to empty by gravity was measured. The time taken to empty 25 mL of curdled milk from the pipette is given in seconds.

[0049] The term "bacteriophage" as used herein has its ordinary meaning as understood in the art, i.e., a virus that selectively infects one or more bacteria. Many bacteriophages are specific to a particular genus, species, or strain. The term "bacteriophage" is synonymous with the term "phage." Bacteriophages include, but are not limited to, bacteriophages that belong to any of the following virus families: Corticoviridae, Cystoviridae, Inoviridae, Leviviridae, Microviridae, Myoviridae, Podoviridae, Siphoviridae, or Tectiviridae. Bacteriophages can be lytic or lysogenic. Lytic bacteriophages are those that do not enter the lysogenic pathway but rather follow the lytic pathway through completion of the lytic cycle. Lytic bacteriophages undergo viral replication, leading to lysis of the cell membrane, rupture of the cell, and release of progeny bacteriophage particles that can infect other cells. Lysogenic bacteriophages are those that are able to enter the lysogenization pathway, in which the bacteriophage becomes a dormant, passive part of the cell's genome before completing its lytic cycle.

[0050] In the context of the present invention, "phage-resistant mutants" refer to bacterial strains that have developed mechanisms to defend against phages. In one embodiment, the lactic acid bacteria according to the invention are resistant to one or more bacteriophages or one or more sets of bacteriophages, in another embodiment, the lactic acid bacteria according to the invention are resistant to the same bacteriophages to which the strain deposited according to the present invention is resistant. Preferably, the lactic acid bacteria according to the present invention are resistant to phage DSM24022. In this context, the term "phage robust" is used interchangeably with the term "phage resistant". Phage-resistant mutants according to the present invention can be obtained as described in Example 1 below.

[0051] In the present specification, the terms "strain derived from", "derived strain" or "mutant" should be understood as a strain derived from another strain (or "mother strain"), for example by means of genetic engineering, radiation and / or chemical treatment, and / or selection, adaptation, screening, etc. Mutants can also be naturally occurring mutants. Derived strains are preferably functionally equivalent mutants, e.g. strains having substantially the same or improved properties as the mother strain in terms of growth and acidification properties. Such derived strains are part of the present invention. In particular, the terms "derived strain" or "mutant" refer to strains obtained by subjecting the mother strain to any conventionally used mutagenesis treatment, including treatment with chemical mutagens such as ethane methanesulfonate (EMS) or N-methyl-N'-nitro-N-nitroguanidine (NTG), UV light, or naturally occurring mutants. Mutants can also be generated by site-directed mutagenesis.

[0052] The mutants may be subjected to several mutagenesis treatments (a single treatment is to be understood as one mutagenesis step followed by a screening / selection step), although it is currently preferred that no more than 20, no more than 10, or no more than 5 treatments are performed. In currently preferred derived strains, less than 1%, or less than 0.1%, less than 0.01%, less than 0.001%, or even less than 0.0001% of the nucleotides in the bacterial genome are altered (e.g. by substitution, insertion, deletion, or a combination thereof) compared to the parent strain.

[0053] In this context, the term "variant" should be understood as a strain that is functionally equivalent to the strain of the invention, having substantially the same or improved properties, for example with regard to viscosity, gel stiffness, mouth-coating, flavor, post-acidification, acidification rate, and / or phage robustness. Such variants can be identified using appropriate screening techniques and are part of the present invention.

[0054] The term "sequence identity" refers to the relationship between two nucleotide sequences or two amino acid sequences. Algorithms for aligning sequences and determining the degree of sequence identity between them are well known in the art. For example, the multiple sequence alignment tool Clustal (https: / / www.ebi.ac.uk / Tools / msa / clustalo / ; Sievers et al., 2011) is used with criteria parameters to determine the degree of sequence identity between two nucleic acid sequences or two amino acid sequences.

[0055] For the purposes of the present invention, the degree of identity between two amino acid sequences is determined using, for example, the Needleman-Wunsch algorithm (Needleman and Wunsch (1970) J. Mol. Biol. 48:443-453), preferably implemented in the EMBOSS package (EMBOSS: The European Molecular Biology Open Software Suite, Rice et al. (2000) Trends in Genetics 16:276-277), version 3.0.0 or later. Optional parameters used are a gap open penalty of 10, a gap extension penalty of 0.5, and the EBLOSUM62 (EMBOSS version of BLOSUM62) substitution matrix. The output of Needle labeled "Longest Identity" (obtained using the -no brief 30 option) is used as the percent identity and is calculated as follows: (identical residues × 100) / (length of alignment − total number of gaps in the alignment)

[0056] Sequence alignment may be performed using blastn, provided by the National Center for Biotechnology Information, at https: / / blast.ncbi.nlm.nih.gov, applying standard parameters.

[0057] In this specification and claims, the conventional one-letter and three-letter codes for amino acid residues are used. For ease of reference, the amino acid changes in the mutants and variants of the invention are described by use of the following nomenclature: amino acid residue in the parent protein; position; substituted amino acid residue(s). According to this nomenclature, for example, the substitution of a valine residue at position 169 with glutamic acid is indicated as Glu169Val or E169V.

[0058] In the context of the present invention, a mutation in a gene ("gene mutation") should be understood as a change in the nucleotide sequence of the genome of an organism that results in a change in the phenotype of said organism, where this change can be a deletion of a nucleotide, a substitution of a nucleotide by another nucleotide, an insertion of a nucleotide, or a frameshift. In the context of the present invention, a "deletion" should be understood as a gene mutation that results in the removal of one or more nucleotides of the nucleotide sequence of the genome of an organism; an "insertion" should be understood as the addition of one or more nucleotides to a nucleotide sequence; a "substitution" (or "point mutation") should be understood as a gene mutation in which a nucleotide of a nucleotide sequence is replaced by another nucleotide. In the context of the present invention, a mutation in a gene refers to a change in the nucleotide sequence of any of the elements contained in a gene. For example, a gene may contain several elements or parts, such as different regulatory sequences (enhancers, silencers, promoters, 5' and 3' UTRs, etc.) and open reading frame regions (including introns and exons). Thus, in the context of the present invention, a mutation in a particular gene should be understood as a change in the nucleotide sequence of said gene, either in the regulatory elements of the gene (e.g., the promoter of the gene) and / or in the open reading frame of the gene (e.g., an exon). If a mutation occurs, for example, in the base sequence of an exon, the mutation may lead to a different amino acid in the translated protein. If a mutation occurs, for example, in the regulatory region of the gene, the mutation may lead to an enhanced (or reduced) expression of the gene, for example an enhanced (or reduced) amount of protein.

[0059] In the context of the present invention, a substitution or mutation of one amino acid or nucleotide for another amino acid or nucleotide at a position corresponding to a position in a sequence means that there may be further mutations (e.g. deletions, insertions, substitutions, etc.) in the mutated amino acid or nucleotide sequence besides the specific substitution or mutation at the particular position (or at the position corresponding to the particular position, e.g. if there is a deletion or insertion in the mutated sequence). Thus, in the context of the present invention, for example, the phrase "The mutation in the branched chain amino acid transporting ATP binding protein LivG (TC 3.A.1.4.1) is a substitution of Glutamic Acid to Valine at the position corresponding to position 169 of SEQ ID NO: 12 and / or a mutation of nucleotide A to nucleotide T at the position corresponding to position 506 of SEQ ID NO: 11" can mean the following: (i) That is, in the mutated amino acid or nucleotide sequence of the branched chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1), there is a substitution (mutation) of Glutamic Acid by Valine at precisely position 169 of SEQ ID NO: 12, or of the nucleotide A by the nucleotide T at precisely position 506 of SEQ ID NO: 11. Naturally, further substitutions or mutations of SEQ ID NO: 12 or SEQ ID NO: 11 are not excluded; (ii) If further mutations such as insertions or deletions are present in the sequence, a particular substitution of glutamic acid to valine or nucleotide A to nucleotide T may no longer be exactly at position 169 of SEQ ID NO: 12 or exactly at position 506 of SEQ ID NO: 11 due to the further mutations such as insertions or deletions. In these cases, the recited substitution of glutamic acid to valine or nucleotide A to nucleotide T must be at the position corresponding to position 169 of SEQ ID NO: 12 or position 506 of SEQ ID NO: 11 taking into account the further mutations in the sequence. The skilled person can identify "a position corresponding to a position in a sequence" by, for example, aligning the sequences and finding a position that corresponds to a position in the original sequence.

[0060] Corresponding meanings apply to the phrases "The mutation in the permease protein of the ABC transporter is a leucine to phenylalanine substitution at the position corresponding to position 190 of SEQ ID NO:4 and / or a nucleotide C to nucleotide T mutation at the position corresponding to position 568 of SEQ ID NO:3" and "The mutation in the peptide deformylase protein is an arginine to cysteine ​​substitution at the position corresponding to position 144 of SEQ ID NO:8 and / or a nucleotide C to nucleotide T mutation at the position corresponding to position 430 of SEQ ID NO:7".

[0061] In this specification and claims, the conventional one-letter code for nucleotides is used according to principles similar to those described above for amino acid nomenclature.

[0062] As used herein, the term "about" (or "approximately") means ±1% of the indicated value, or the term "about" means ±2% of the indicated value, or the term "about" means ±5% of the indicated value, or the term "about" means ±10% of the indicated value, or the term "about" means ±20% of the indicated value, or the term "about" means ±30% of the indicated value, and preferably, the term "about" means exactly the indicated value (±0%).

[0063] Throughout this specification and the claims, the word "comprise" and variations of this word (e.g., "comprising," "having," "including," "containing") are generally open ended and therefore do not exclude other features which may be, for example, technical features, additives, components, or steps. However, whenever the word "comprise" is used in this specification, this also includes the specific embodiment to which this word is understood as limiting; in this particular embodiment, the word "comprise" has the meaning of the term "consisting of."

[0064] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the present invention (particularly in the context of the accompanying claims) should be construed to include both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The recitation of numerical ranges herein is intended merely to serve as a shorthand method for individually referring to each value falling within the range, unless otherwise indicated herein, and each value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by context.

[0065] Any examples or exemplary language used herein (e.g., "such as"), unless specifically claimed, is intended merely to better illustrate the invention and does not pose a limitation on the scope of the invention. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0066] According to the invention, the viscosity can be (preferably) measured as described in Examples 2 and 3. According to the invention, the suction can be (preferably) measured as described in Example 4. According to the invention, the rheological properties of the lactic acid bacteria or blends, such as the shear stress, can be (preferably) measured as described in Example 5.

[0067] Streptococcus thermophilus strains The inventors have surprisingly identified a S. thermophilus strain that meets the needs of the industry. The new strain, for example, when compared to its mother strain, shows improved rheological properties (e.g., texture) when applied alone or as part of a mixed culture in dairy matrices. The new S. thermophilus strain has the potential to be used in dairy cultures, such as yogurt cultures, to obtain improved rheological parameters, such as shear stress, viscosity and gel hardness of the final product. Rheology is closely related to the sensory quality of the product, and therefore the interplay between rheology and taste in the final product is of utmost importance.

[0068] The inventors have surprisingly found that S. thermophilus strains carrying a mutation in the branched-chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene have better texture properties than their parent strains, i.e., strains that do not carry the same mutation in the branched-chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene. In particular, the inventors have found that a mutation in the branched-chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene (wherein the mutation is a glutamic acid to valine substitution at the position corresponding to position 169 of SEQ ID NO: 12) is associated with better texture properties. For example, the inventors have surprisingly found that an S. thermophilus strain carrying a mutation in the branched chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene, where the mutation is a substitution of nucleotide A to nucleotide T at the position corresponding to position 506 of SEQ ID NO: 11, exhibits better texture properties than the parent strain. This is shown in the present example. Thus, the inventors have surprisingly found that S. thermophilus strains having a valine at the position corresponding to position 169 of SEQ ID NO:12 and / or a T at the position corresponding to position 506 of SEQ ID NO:11 (branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) gene) exhibit better texture properties than S. thermophilus strains that do not have a valine at the position corresponding to position 169 of SEQ ID NO:12 (e.g. a strain which may have glutamic acid at the position corresponding to position 169 of SEQ ID NO:12) and / or a T at the position corresponding to position 506 of SEQ ID NO:11 (e.g. a strain which may have an A at the position corresponding to position 506 of SEQ ID NO:11).

[0069] Thus, a first aspect of the invention relates to (i) an S. thermophilus strain having a mutation in the branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) gene, wherein the mutation is preferably a substitution of Glutamic Acid to Valine at the position corresponding to position 169 of SEQ ID NO: 12. In another aspect, the invention relates to (i) an S. thermophilus strain having a mutation in the branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) gene, wherein the mutation is preferably a substitution of nucleotide A to nucleotide T at the position corresponding to position 506 of SEQ ID NO: 11. Thus, the invention further relates to an S. thermophilus strain (branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) gene) having a Valine at the position corresponding to position 169 of SEQ ID NO: 12 and / or a T at the position corresponding to position 506 of SEQ ID NO: 11.

[0070] Furthermore, the inventors have surprisingly found that S. thermophilus strains carrying a mutation in an ABC transporter permease protein gene have better texture properties than their mother strains, i.e. than strains not carrying the same mutation in the ABC transporter permease protein gene. In particular, the inventors have found that a mutation in the ABC transporter permease protein gene, where the mutation is a leucine to phenylalanine substitution at the position corresponding to position 190 of SEQ ID NO: 4, is associated with better texture properties. For example, the inventors have surprisingly found that S. thermophilus strains carrying a mutation in the ABC transporter permease protein gene, where the mutation is a substitution of the nucleotide C to the nucleotide T at the position corresponding to position 568 of SEQ ID NO: 3, exhibit better texture properties than the mother strain. This is shown in the examples. Thus, the inventors have surprisingly found that S. thermophilus strains having a phenylalanine at position corresponding to position 190 of SEQ ID NO:4 and / or a T at position corresponding to position 568 of SEQ ID NO:3 (the permease protein gene of the ABC transporter) exhibit better texture properties than S. thermophilus strains that do not have a phenylalanine at position corresponding to position 190 of SEQ ID NO:4 (e.g. a strain that has a leucine at position corresponding to position 190 of SEQ ID NO:4) and / or that do not have a T at position corresponding to position 568 of SEQ ID NO:3 (e.g. a strain that has a C at position corresponding to position 568 of SEQ ID NO:3).

[0071] Thus, an S. thermophilus strain of the invention has (ii) a mutation in an ABC transporter permease protein gene, wherein the mutation is preferably a leucine to phenylalanine substitution at the position corresponding to position 190 of SEQ ID NO: 4. For example, an S. thermophilus strain of the invention has (ii) a mutation in an ABC transporter permease protein gene, wherein the mutation is preferably a nucleotide C to nucleotide T substitution at the position corresponding to position 568 of SEQ ID NO: 3. Thus, the invention further relates to an S. thermophilus strain having (ii) a phenylalanine at the position corresponding to position 190 of SEQ ID NO: 4 and / or a T at the position corresponding to position 568 of SEQ ID NO: 3 (ABC transporter permease protein gene).

[0072] Furthermore, the inventors have surprisingly found that S. thermophilus strains carrying a mutation in the peptide deformylase protein gene have better texture properties than their mother strains, i.e., strains that do not carry the same mutation in the peptide deformylase protein gene. In particular, the inventors have found that a mutation in the peptide deformylase protein gene, where the mutation is a substitution of arginine with cysteine ​​at the position corresponding to position 144 of SEQ ID NO:8, is associated with better texture properties. For example, the inventors have surprisingly found that S. thermophilus strains carrying a mutation in the peptide deformylase protein gene, where the mutation is a substitution of nucleotide C with nucleotide T at the position corresponding to position 430 of SEQ ID NO:7, exhibit better texture properties than the mother strain. This is shown in the examples. Thus, the inventors have surprisingly found that S. thermophilus strains having a cysteine ​​at position corresponding to position 144 of SEQ ID NO:8 and / or a T at position corresponding to position 430 of SEQ ID NO:7 (peptide deformylase protein gene) exhibit better texture properties than S. thermophilus strains that do not have a cysteine ​​at position corresponding to position 144 of SEQ ID NO:8 (e.g. a strain having an arginine at position corresponding to position 144 of SEQ ID NO:8) and / or that do not have a T at position corresponding to position 430 of SEQ ID NO:7 (e.g. a strain having a C at position corresponding to position 430 of SEQ ID NO:7).

[0073] Thus, an S. thermophilus strain of the invention has (iii) a mutation in a peptide deformylase protein gene, wherein the mutation is preferably a substitution of arginine to cysteine ​​at position s corresponding to position 144 of SEQ ID NO: 8. For example, an S. thermophilus strain of the invention has (iii) a mutation in a peptide deformylase protein gene, wherein the mutation is preferably a substitution of nucleotide C to nucleotide T at the position corresponding to position 430 of SEQ ID NO: 7. Thus, the invention relates to an S. thermophilus strain (peptide deformylase protein gene) having (iii) a cysteine ​​at the position corresponding to position 144 of SEQ ID NO: 8 and / or a T at the position corresponding to position 430 of SEQ ID NO: 7.

[0074] The S. thermophilus strain of the invention preferably has at least two of the above mutations (i) to (iii), and preferably has mutations (i) and (ii), namely (i) a mutation in the branched chain amino acid transporting ATP binding protein LivG (TC 3.A.1.4.1) gene, preferably a substitution of Glutamic Acid to Valine at the position corresponding to position 169 of SEQ ID NO: 12, where the mutation is preferably a substitution of nucleotide A to nucleotide T at the position corresponding to position 506 of SEQ ID NO: 11, and (ii) a mutation in the permease protein gene of an ABC transporter, where the mutation is preferably a substitution of leucine to phenylalanine at the position corresponding to position 190 of SEQ ID NO: 4, or preferably a substitution of nucleotide C to nucleotide T at the position corresponding to position 568 of SEQ ID NO: 3. In another embodiment, the S. thermophilus strain of the invention has mutations (i) and (iii) as described above, or has mutations (ii) and (iii) as described above.

[0075] In one embodiment, the S. thermophilus strain of the invention has all three mutations in the protein and / or nucleotide sequence as set out in (i) to (iii) above.

[0076] In one embodiment, the branched chain amino acid transport ATP binding protein LivG (TC 3.A.1.4.1) gene of the S. thermophilus strain of the invention has a T at a position corresponding to position 506 of SEQ ID NO: 11, and / or the branched chain amino acid transport ATP binding protein LivG (TC 3.A.1.4.1) has a valine at a position corresponding to position 169 of SEQ ID NO: 12. In a further preferred embodiment, the ABC transporter permease protein gene of the S. thermophilus strain of the invention has a T at a position corresponding to position 568 of SEQ ID NO: 3, and / or the ABC transporter permease protein has a phenylalanine at a position corresponding to position 190 of SEQ ID NO: 4. In another embodiment, the S. thermophilus strain of the invention has both (i) and (ii) above. In another embodiment, the S. thermophilus strain of the invention has (i) and (iii) above. In a further embodiment, the S. thermophilus strain of the invention has (ii) and (iii) above. In a preferred embodiment, the S. thermophilus strain of the invention has (i), (ii) and (iii) above.

[0077] Preferably, the S. thermophilus strain of the invention, when used to ferment milk, produces a higher shear stress and / or higher efflux time in a viscosity pipette test (measured as described herein and in the Examples) than a strain that does not comprise any of the above mutations (i), (ii) or (iii). In one embodiment of the invention, the strain that does not comprise any of the above mutations (i), (ii) or (iii) is the mother strain from which the S. thermophilus strain of the invention is derived. In one aspect of the invention, the strain that does not comprise any of the above mutations (i), (ii) or (iii) is strain DSM22587.

[0078] In one embodiment of the invention, the mutant strain is phage resistant, substantially phage resistant and / or has increased phage resistance compared to its mother strain. This means that the mother strain is susceptible to infection (lysis) by a phage, whereas the mutant strain is resistant to infection (lysis) by the same phage. Preferably, the S. thermophilus strain of the invention is resistant to phage DSM24022. In one embodiment, the S. thermophilus strain of the invention is a phage resistant mutant from strain DSM22587. Preferably, the S. thermophilus strain of the invention is a mutant from strain DSM22587, which mutant is resistant to phage DSM24022.

[0079] Even more preferably, the S. thermophilus strain of the invention is DSM22933 or a mutant or variant thereof. Preferably, the mutant or variant exhibits the same or similar textural properties as DSM22933, e.g. the same or similar shear stress and / or the same or similar viscosity properties. Thus, it is intended that the S. thermophilus strains of the invention, including mutants and variants of DSM22933, exhibit at least the same or similar shear stress and / or viscosity properties and / or textural properties as DSM22933, as defined in the present examples. Thus, the invention further provides S. thermophilus strain DSM22933 or a mutant or variant thereof.

[0080] In the present context, the term "same or similar shear stress" should be understood as a range from 10% below the shear stress characteristics of DSM22933 to 10% above the shear stress characteristics of DSM22933, which range may be 9% below / above the shear stress characteristics of DSM22933, such as 8% below / above the shear stress characteristics of DSM22933, such as 7% below / above the shear stress characteristics of DSM22933. For example, it may be less than / exceeding 6% of the shear stress characteristic of DSM22933, such as less than / exceeding 5% of the shear stress characteristic of DSM22933, such as less than / exceeding 4% of the shear stress characteristic of DSM22933, such as less than / exceeding 3% of the shear stress characteristic of DSM22933, such as less than / exceeding 2% of the shear stress characteristic of DSM22933, or less than / exceeding 1% of the shear stress characteristic of DSM22933, etc. The shear stress characteristic of DSM22933 is measured as described herein or as described in Example 5. For example, the shear stress characteristic of DSM2293 may be measured in a mixed culture as described in Example 5. For example, the shear stress characteristic of DSM2293 may be measured as follows:

[0081] Shear stress was obtained by inoculating milk (protein 3.6%, fat 1.5% or 3%) with the same microbial cultures. Milk was heated for 5 min at 95°C, cooled to the inoculation temperature (43°C) and then inoculated with 30% of the texturing strain to be tested, 60% of another S. thermophilus strain and 10% of Lb. bulgaricus strain or milk was heated for 5 min at 95°C, cooled to the inoculation temperature (43°C) and then inoculated with 50% of the texturing strain to be tested, 25% of another S. thermophilus strain and 25% of Lb. bulgaricus strain, preferably DSM26419. Fermentation was carried out at 43°C to pH 4.60, then cooled to 6°C and stored at 6°C for 7 days. After storage, the fermented milk was gently stirred with a rod equipped with a bored disc until the sample was homogenous. The shear stress of the samples was evaluated at 13°C using a rheometer (Anton Paar Physica Rheometer, automatic sample changer, Anton Paar) with the following settings: - Waiting time (to restore some structure) - 5 minutes without rocking or rotating -Rotation (300s -1(to measure the shear stress at -Y'=[0.2707-300]s -1 , y'=[275-0.2707]s -1

[0082] 21 measurement points in 210 seconds (1 point every 10 seconds) for 300 seconds -1 and 0.2707s at 21 measurement points (1 point every 10 seconds) over 210 seconds. -1 For data analysis, the shear rate was 300 s -1 The shear stress at

[0083] In the present context, the term "same or similar viscosity characteristics" should be understood as a range from less than 10% of the viscosity characteristics of DSM22933 to more than 10% of the viscosity characteristics of DSM22933, which may be less than / more than 9% of the viscosity characteristics of DSM22933, such as less than / more than 8% of the viscosity characteristics of DSM22933, such as less than / more than 7% of the viscosity characteristics of DSM22933, such as less than / more than 6% of the viscosity characteristics of DSM22933. For example, it may be less than / more than 5% of the viscosity characteristics of DSM22933, such as less than / more than 4% of the viscosity characteristics of DSM22933, such as less than / more than 3% of the viscosity characteristics of DSM22933, such as less than / more than 2% of the viscosity characteristics of DSM22933, or less than / more than 1% of the viscosity characteristics of DSM22933, etc. The viscosity characteristics of DSM22933 are measured as described herein and / or in Examples 2-3. For example, the viscosity characteristics can be measured by a viscosity pipette test, i.e., measuring the efflux time from a graduated pipette. A longer efflux time corresponds to a higher viscosity. For example, the viscosity pipette test can be performed as follows.

[0084] Skim milk inoculated with 1% of the test strain (cultured overnight at 37°C using skim milk) was used as coagulated milk, which was then cultured at 42°C or 37°C for 20 hours. The viscosity of the coagulated milk was measured with a 25mL measuring pipette, and the time it took to flow out of the pipette was measured three times. The coagulated milk was carefully stirred with a spoon to homogenize it. A 25mL measuring pipette was then filled, and the time it took for the pipette to empty by gravity was measured. The time it took for 25mL of the coagulated milk to empty from the pipette is shown in seconds.

[0085] The viscosity pipette test can be performed with the strain itself (single strain, e.g., Example 2) or with a mixed culture of S. thermophilus and an acidified Lb bulgaricus strain, preferably strain DSM19251, and optionally with 1% yeast extract (e.g., Example 3).

[0086] The above "characteristics" should be understood in the context of the definition section, where methods for appropriately measuring shear stress or viscosity are described. Methods for determining the texture of fermented products, such as dairy products, including measuring the shear stress or viscosity characteristics of the fermented product, are readily available and known in the art, and are exemplified herein.

[0087] In one embodiment, the Streptococcus thermophilus strains of the invention have improved texture characteristics as described above, while retaining the growth and acidification characteristics of their parental (mother) strain.

[0088] Compositions containing Streptococcus thermophilus strains The present invention also provides compositions and starter cultures comprising the S. thermophilus strains of the invention as described above.

[0089] Lactic acid bacteria (LAB), including bacteria of the species S. thermophilus, are usually supplied to the dairy industry as frozen (F-DVS®) or freeze-dried (FD-DVS®) cultures for bulk starter growth, or as so-called "direct vat set" (DVS®) cultures intended for direct inoculation of fermentation vessels or vats for the production of dairy products, such as fermented dairy products. Such lactic acid bacteria cultures are commonly called "starter cultures" or "starters". Thus, the present invention further provides a starter culture or starter, preferably a yogurt starter culture, comprising the strain of the present invention as described above. The composition or starter culture of the present invention may be frozen or lyophilized. Furthermore, the composition or starter culture of the present invention may be provided in liquid form. Thus, in one embodiment, the composition is in frozen, dried, lyophilized or liquid form. Preferably, the composition and / or starter culture of the present invention is in frozen, spray-dried, freeze-dried, vacuum-dried, air-dried, tray-dried or liquid form.

[0090] The composition or starter culture of the present invention may also further comprise a cryoprotectant, a lyoprotectant, an antioxidant, a nutrient, a filler, a flavouring or a mixture thereof. The composition preferably comprises a cryoprotectant, a lyoprotectant, an antioxidant and / or a nutrient, more preferably a cryoprotectant, a lyoprotectant and / or an antioxidant, and most preferably one or more of a cryoprotectant or a lyoprotectant, or both. The use of protective agents such as cryoprotectants and lyoprotectants is known to those skilled in the art. Suitable cryoprotectants or lyoprotectants include mono-, di-, tri- and polysaccharides (such as glucose, mannose, xylose, lactose, sucrose, trehalose, raffinose, maltodextrin, starch and gum arabic (acacia)), polyols (such as erythritol, glycerol, inositol, mannitol, sorbitol, threitol, xylitol), amino acids (such as proline, glutamic acid), complex substances (such as skim milk, peptone, gelatin, yeast extract) and inorganic compounds (such as sodium tripolyphosphate).

[0091] In one embodiment, the composition or starter culture according to the invention may comprise one or more cryoprotectants selected from the group consisting of inosine-5'-monophosphate (IMP), adenosine-5'-monophosphate (AMP), guanosine-5'-monophosphate (GMP), uranosine-5'-monophosphate (UMP), cytidine-5'-monophosphate (CMP), adenine, guanine, uracil, cytosine, adenosine, guanosine, uridine, cytidine, hypoxanthine, xanthine, hypoxanthine, orotidine, thymidine, inosine, and derivatives of any such compounds. Suitable antioxidants include ascorbic acid, citric acid and its salts, gallic acid, cysteine, sorbitol, mannitol, maltose. Suitable nutrients include sugars, amino acids, fatty acids, minerals, trace elements, vitamins (e.g., vitamin B family, vitamin C). The composition may optionally contain further substances including bulking agents (lactose, maltodextrin, etc.) and / or flavourings. In one embodiment of the invention, the cryoprotectant is an agent or mixture of agents that has a booster effect in addition to its cryoprotective properties.

[0092] The expression "booster effect" is used to describe the situation where a cryoprotectant, when inoculated into the medium to be fermented or converted, confers increased metabolic activity (booster effect) to the thawed or reconstituted culture. Viability and metabolic activity are not synonymous concepts. Commercially available frozen or freeze-dried cultures may have lost a significant part of their metabolic activity but may retain their viability. For example, cultures may lose their acidogenic (acidifying) activity even when stored for shorter periods. Therefore, viability and boosting effect must be evaluated by different assays. Viability is evaluated by viability assays such as the measurement of colony forming units, whereas boosting effect is evaluated by quantifying the relative metabolic activity of the thawed or reconstituted culture relative to the viability of the culture. The term "metabolic activity" refers to the oxygen scavenging activity of the culture, its acidogenic activity, i.e., the production of, for example, lactic acid, acetic acid, formic acid and / or propionic acid or their metabolites, for example, the production of aroma compounds such as acetaldehyde (α-acetolactate, acetoin, diacetyl and 2,3-butylene glycol (2,3-butanediol)).

[0093] In one embodiment, the composition or starter culture of the invention contains or comprises 0.2% to 20% of a cryoprotectant or mixture of agents, measured as w / w % of the material. However, it is preferred to add the cryoprotectant or mixture of agents in an amount within the ranges of 0.2% to 15%, 0.2% to 10%, 0.5% to 7%, and 1% to 6% by weight, including within the ranges of 2% to 5% of the cryoprotectant or mixture of agents, measured as w / w % of the weight of the frozen material. In one embodiment, the culture comprises about 3% of the cryoprotectant or mixture of agents, measured as w / w % of the material by weight. An amount of about 3% of the cryoprotectant corresponds to a concentration in the 100 mM range. It should be appreciated that for each aspect of an embodiment of the invention, the ranges can be increments of the stated ranges.

[0094] In a further aspect, the composition or starter culture of the invention contains or comprises an ammonium salt (e.g. an ammonium salt of an organic acid (such as ammonium formate and ammonium citrate) or an ammonium salt of an inorganic acid) as a booster (e.g. a growth booster or acidification booster) for bacterial cells (e.g. cells belonging to the species S. thermophilus (e.g. (substantially) urease negative bacterial cells). The terms "ammonium salt", "ammonium formate" and the like should be understood as a source of a combination of salts or ions. The term "source" of, for example, "ammonium formate" or "ammonium salt" refers to a compound or mixture of compounds that provides ammonium formate or an ammonium salt when added to a culture of cells. In some embodiments, the ammonium source releases ammonium into the growth medium, while in other embodiments, the ammonium source is metabolized to produce ammonium. In some preferred embodiments, the ammonium source is exogenous. In some particularly preferred embodiments, the ammonium is not provided by the dairy substrate. It should of course be understood that ammonia may be added instead of an ammonium salt. Thus, the term ammonia salt refers to ammonia (NH3), NH4OH, NH4 + etc.

[0095] In one embodiment, the compositions of the present invention can include thickeners and / or stabilizers such as pectin (e.g., HM pectin, LM pectin), gelatin, CMC, soy fiber / soy polymers, starch, modified starch, carrageenan, alginates, and guar gum.

[0096] The composition or starter culture of the invention can be a mixture or kit-of-parts: i) a Streptococcus thermophilus strain of the invention, preferably strain DSM22933, and ii) Strains belonging to Lactobacillus delbrueckii subspecies bulgaricus.

[0097] To obtain the best combination of acidity, taste and texture in dairy products such as yogurt, a combination of S. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus is often applied.

[0098] In one embodiment, the mixture or kit-of-parts may comprise one or more Lactobacillus delbrueckii subsp. bulgaricus strain(s), optionally in combination with S. thermophilus strain(s) of the present invention.

[0099] For example, a mixture or kit of parts may include a S. thermophilus strain of the invention in combination with Lactobacillus delbrueckii subsp. bulgaricus strain DSM 19251. In one embodiment, a mixture or kit of parts may include S. thermophilus strain DSM 22933 in combination with Lactobacillus delbrueckii subsp. bulgaricus strain DSM 19251.

[0100] Furthermore, the composition of the present invention may further comprise a yeast extract.Thus, the composition of the present invention may comprise a Streptococcus thermophilus strain of the present invention, a strain belonging to the Lactobacillus delbrueckii subsp. bulgaricus strain, preferably a strain as defined above, optionally further Streptococcus thermophilus strains, and optionally a yeast extract.

[0101] The term "mixture" means that the S. thermophilus strain and the Lactobacillus delbrueckii subsp. bulgaricus strain are physically mixed together. In one embodiment, the S. thermophilus strain and the Lactobacillus delbrueckii subsp. bulgaricus strain are in the same box or in the same pouch.

[0102] In contrast, the expression "kit of parts" including S. thermophilus and L. bulgaricus strains means that the culture of S. thermophilus strain and the culture of L. bulgaricus strain are physically separated but intended to be used together. Thus, the culture of S. thermophilus strain and the culture of L. bulgaricus strain are in different boxes or pouches. In one embodiment, the culture of S. thermophilus strain and the culture of L. bulgaricus strain are under the same format, i.e. in frozen format, in the form of pellets or frozen pellets, in powder form such as dried or freeze-dried powder.

[0103] In one embodiment of the present invention, the composition comprises 10 4 ~10 12 CFU (colony forming units) / g of S. thermophilus strain, e.g., 10 5 ~10 11 CFU / g, e.g., 10 6 ~10 10 CFU / g, or for example, 10 7 ~10 9 In one embodiment, the composition comprises 10 4 ~10 12 CFU / g of L. bulgaricus strain, e.g., 10 5 ~10 11 CFU / g, e.g., 10 6 ~10 10 CFU / g, or e.g., 10 7 ~10 9 CFU / g of L. bulgaricus strain.

[0104] Fermented food manufacturing method The present invention further relates to a method for producing a fermented food product comprising at least one step in which at least one of the S. thermophilus strains as defined in the first aspect of the invention and / or the composition or starter culture as defined in the second aspect of the invention is used. The production of the food product is carried out by methods known to the person skilled in the art.

[0105] Depending on the product to be produced, the substrate may be a dairy substrate. A dairy substrate is particularly preferred when the end product is a fermented dairy product such as yoghurt, buttermilk or kefir. Thus, in one embodiment, the method in any of its embodiments comprises fermenting a dairy substrate with a strain as defined in the first aspect and / or a composition as described in the second aspect of the invention.

[0106] The invention therefore provides a food product comprising the strain and / or composition of the invention. Preferably, the food product is a dairy product, and the method in any of its embodiments comprises fermenting a dairy substrate (also referred to in the context of the present invention as "dairy substrate") with at least one S. thermophilus and / or with a composition or starter culture according to the invention.

[0107] The food products of the present invention may advantageously further comprise "thickening agents" and / or "stabilizers" such as pectin (e.g., HM pectin, LM pectin), gelatin, CMC, soy fiber / soy polymers, starch, modified starch, carrageenan, alginates, and guar gum.

[0108] In one embodiment, the food product is a dairy product as defined above. In a particular embodiment of the invention, the fermented dairy product is selected from the group consisting of yoghurt, mozzarella cheese, kefir, sour cream, cheese, quark. Yoghurt is particularly preferred. In one embodiment of the invention, the fermented dairy product contains a further food product selected from the group consisting of fruit drinks, cereal products, fermented cereal products, chemically acidified cereal products, soy milk products, fermented soy milk products, and any mixtures thereof.

[0109] In one embodiment, the fermented product further comprises an ingredient selected from the group consisting of fruit concentrates, syrups, probiotic bacterial strains or cultures, colorants, thickeners, flavoring agents, preservatives, and mixtures thereof.

[0110] Similarly, enzymes can be added to the substrate, e.g., milk substrate, before, during and / or after fermentation, the enzymes being selected from the group consisting of enzymes capable of cross-linking proteins, transglutaminase, aspartic protease, chymosin, rennet and combinations thereof. In one embodiment, the fermented product can be in the form of a stirred product, a set product or a drinkable product.

[0111] Fermented milk products usually contain protein at levels of 1.0% to 12.0% by weight, preferably 2.0% to 10.0% by weight. In a particular embodiment, sour cream contains protein at levels between 1.0% and 5.0% by weight, preferably between 2.0% and 4.0% by weight. In a particular embodiment, quark contains protein at levels of 4.0% to 12.0% by weight, preferably 5% to 10.0% by weight.

[0112] Preferably, the food product has a texture (as described in the present invention, such as in Examples 2-5) compared to a food product produced in a comparable manner without the use of at least one of the S. thermophilus strains described in the present invention and / or the use of a composition or starter culture according to the present invention.

[0113] Fermented food products obtained directly by the method of the present invention In one embodiment, the present invention also relates to a fermented food product, either directly obtained by the method of the present invention, or comprising a Streptococcus thermophilus strain according to the present invention, or comprising a composition according to the present invention. Thus, an aspect of the present invention is also a fermented product comprising a Streptococcus thermophilus strain of the present invention and / or a composition of the present invention. The fermented product is preferably a dairy product, such as yoghurt.

[0114] Method for producing the Streptococcus thermophilus strain of the present invention The invention also provides a method for producing the Streptococcus thermophilus strains and / or compositions according to the invention, the method comprising: (i) providing a lactic acid bacteria strain as a mother strain; (ii) exposing the mother strain to an optional mutagenesis treatment using a chemical mutagen or treatment with UV light, and / or subjecting the mother strain to site-directed mutagenesis as defined herein; (iii) The following mutations: a) Mutations in the branched-chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene; b) a mutation in the gene for the permease protein of an ABC transporter; and / or c) Mutations in the peptide deformylase protein gene Screening for mutant strains containing at least one, preferably two, and more preferably all three of the following: wherein preferably the mutant strain exhibits improved textural properties as defined herein compared to the mother strain, and even more preferably the resulting Streptococcus thermophilus strain exhibits the same or improved textural properties as defined herein compared to strain DSM 22933. Thus, the method of the invention may comprise a further screening step (iv), i.e. screening for mutant strains exhibiting improved textural properties as defined herein compared to the mother strain (e.g. producing a higher shear stress and / or viscosity than the mother strain).

[0115] Preferably, the mother strain in (i) is the deposited strain DSM22587.

[0116] Streptococcus thermophilus strains as defined in the present invention can also be generated by site-directed mutagenesis (see step (ii) above). A specific DNA fragment is amplified by PCR using an oligonucleotide carrying a mutated nucleotide in the branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) and / or in the permease protein and / or peptide deformylase protein of the ABC transporter. The PCR fragment carrying the desired mutation is cloned into a vector plasmid and transformed into a S. thermophilus target strain, incorporating the mutation into the chromosome and exchanging the wild-type protein region by recombination. Isolation of the strains is carried out as described above. Step (iii) above can therefore also be screening for mutant strains containing at least one, preferably two and even more preferably all three of the following amino acids and / or nucleotides in the following positions: a) a valine at a position corresponding to position 169 of SEQ ID NO: 12 and / or a T at a position corresponding to position 506 of SEQ ID NO: 11 (branched-chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene); b) a phenylalanine at a position corresponding to position 190 of SEQ ID NO: 4 and / or a T at a position corresponding to position 568 of SEQ ID NO: 3 (permease protein gene of ABC transporter); and / or c) a cysteine ​​at a position corresponding to position 144 of SEQ ID NO:8, and / or a T at a position corresponding to position 430 of SEQ ID NO:7 (peptide deformylase protein gene).

[0117] In one embodiment, the mutation in the branched chain amino acid transporting ATP binding protein LivG (TC 3.A.1.4.1) gene (a) is a substitution of glutamic acid to valine at the position corresponding to position 169 of SEQ ID NO: 12 and / or a mutation of nucleotide A to nucleotide T at the position corresponding to position 506 of SEQ ID NO: 11. In one embodiment, the mutation in the ABC transporter permease protein gene (b) is a substitution of leucine to phenylalanine at the position corresponding to position 190 of SEQ ID NO: 4 and / or a mutation of nucleotide C to nucleotide T at the position corresponding to position 568 of SEQ ID NO: 3. In another preferred embodiment, the mutation in the peptide deformylase protein gene (c) is a substitution of arginine to cysteine ​​at the position corresponding to position 144 of SEQ ID NO: 8 and / or a mutation of nucleotide C to nucleotide T at the position corresponding to position 430 of SEQ ID NO: 7.

[0118] Furthermore, the present invention provides a method for producing a Streptococcus thermophilus strain that exhibits improved texture characteristics as defined herein compared to a mother strain (e.g., producing higher shear stress and / or viscosity than the mother strain) when the bacteria is used to ferment milk, comprising: a) providing a lactic acid bacteria strain as a mother strain; b) exposing the mother strain to a bacteriophage capable of lysing the mother strain; c) isolating mutants of a mother strain, the mother strain being not lysed by the bacteriophage and comprising: i. Mutations in the branched-chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene; ii. a mutation in the gene for the permease protein of an ABC transporter; and / or iii. Mutations in the peptide deformylase protein gene having one, two, or three mutations selected from the group consisting of: e) screening for mutant strains that, when used to ferment milk, exhibit improved texture properties as defined herein compared to the mother strain (e.g., producing higher shear stress and / or viscosity than the mother strain). Includes.

[0119] Preferably, the method of the invention as described above comprises a step of incubating the exposed bacterial cells in a growth medium prior to step c) above. Preferably, the mother strain is strain DSM 22587. Preferably, the bacteriophage capable of lysing the mother strain of step b) above is strain DSM 24022.

[0120] In one embodiment, the (i) mutation in the branched chain amino acid transporting ATP binding protein LivG (TC 3.A.1.4.1) gene is a substitution of glutamic acid to valine at the position corresponding to position 169 of SEQ ID NO: 12, and / or a mutation of nucleotide A to nucleotide T at the position corresponding to position 506 of SEQ ID NO: 11. In one embodiment, the mutation in the ABC transporter permease protein gene is a substitution of leucine to phenylalanine at the position corresponding to position 190 of SEQ ID NO: 4, and / or a mutation of nucleotide C to nucleotide T at the position corresponding to position 568 of SEQ ID NO: 3. In one embodiment, the mutation in the peptide deformylase protein gene is a substitution of arginine to cysteine ​​at the position corresponding to position 144 of SEQ ID NO: 8, and / or a mutation of nucleotide C to nucleotide T at the position corresponding to position 430 of SEQ ID NO: 7.

[0121] Step d) above may also comprise introducing at least one, preferably two and more preferably all three of the following amino acids / nucleotides at the following positions: a) a valine at a position corresponding to position 169 of SEQ ID NO: 12 and / or a T at a position corresponding to position 506 of SEQ ID NO: 11 (branched-chain amino acid transport ATP-binding protein LivG (TC 3.A.1.4.1) gene); b) a phenylalanine at a position corresponding to position 190 of SEQ ID NO: 4 and / or a T at a position corresponding to position 568 of SEQ ID NO: 3 (permease protein gene of ABC transporter); and / or c) a cysteine ​​at a position corresponding to position 144 of SEQ ID NO:8 and / or a T at a position corresponding to position 430 of SEQ ID NO:7 (peptide deformylase protein gene).

[0122] Above step d) (e.g. introducing at least one, preferably two, more preferably all three of the described mutations) may be carried out by exposing the mother strain to any commonly used mutagenesis treatment, including treatment with chemical mutagens or UV light, and / or by site-directed mutagenesis as defined herein.

[0123] Methods for determining the texture of fermented products, such as dairy products, including measuring the shear stress or viscosity of the fermented product (e.g., by the viscosity pipette test described herein), are readily available and known in the art, and are described and exemplified herein.

[0124] In one embodiment, the Streptococcus thermophilus strains of the invention and / or obtained directly by the above method generate an improved shear stress of at least 1% when compared to the parent strain, for example 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20% or more when compared to the parent strain. The shear stress properties of the Streptococcus thermophilus strains of the invention and / or obtained directly by the above method can be measured in mixed cultures as described in Example 5. Furthermore, the shear stress properties of DSM2293 can be measured on its own strain as described above.

[0125] In one embodiment, the Streptococcus thermophilus strains of the invention and / or obtained directly by the method described above, when inoculated with an amount of 0.02% FD-DVS starter culture, produce a shear stress measured at 300 1 / s (Pa) that is improved by at least 1% compared to the mother strain (e.g., 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20% or more compared to the mother strain) after less than about 5 hours of growth (to a pH of about 4.60) in milk (3.6% protein and 1.5% or 3% fat) at 43° C.

[0126] In one embodiment, the Streptococcus thermophilus strain of the invention and / or the Streptococcus thermophilus strain obtained directly by the above method produces an improved flow-out time of milk coagulated with said strain from a pipette of at least 1% when compared to its mother strain (e.g., 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20% or more when compared to its mother strain). The pipette viscosity test can be performed as described in Example 2. The pipette viscosity test can be performed as a mixed culture as described in Example 3.

[0127] "Texture" or "mouthfeel" refers to the physical and chemical interactions of a product in the mouth.

[0128] Use of the Streptococcus thermophilus strains of the invention and / or the compositions of the invention One aspect of the invention relates to the use of the Streptococcus thermophilus strains and / or compositions of the invention for the manufacture of a fermented product, wherein again the fermented product may be a dairy product.

[0129] Any combination of the above-described elements, aspects, and embodiments in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein or clearly contradicted by context. EXAMPLES

[0130] Example 1: Phage-resistant mutants of Streptococcus thermophilus strain DSM22587 Phage-resistant mutants were isolated by incubating an overnight culture of DSM22587 in 0.1 mL of M17-2% lactose at 1 × 10 8 The mutants were generated from the parent strain DSM22587 on M17-2% lactose agar plates containing 10 mM MgCl2 / CaCl2 after plating with 0.1 mL of phage DSM24022 containing phage particles and incubating overnight at 37 °C. Among several mutants, strain DSM22933 was colony purified three times and retested for plaques on M17 lactose agar plates at 37 °C using phage DSM24022 for phage challenge, confirming phage resistance (not a single plaque was observed in the plaque test). DSM22933 was also tested in a milk acidification test and showed acidification activity comparable to the parent strain.

[0131] The genome of DSM22933 was sequenced at Chr. Hansen A / S as described in AgersΦ et al., 2018. Briefly, total DNA was purified and used to prepare 250bp paired-end libraries for genome sequencing using an Illumina MiSeq system. Sequence reads were subjected to quality trimming (Phred score <25) and assembled into contigs using the de novo assembly algorithm in CLC Genomics Workbench, version 10.1.1 (CLC Bio, Qiagen Bioinformatics). The resulting genome assembly was filtered by removing contigs with coverage <15× and / or <20% of the median coverage of the assembly. The consensus sequence of the remaining contigs was exported in FASTA format, which was called the draft genome sequence and was used in subsequent sequence analysis.

[0132] [Table 1]

[0133] Example 2: Viscosity pipette test of DSM22933 as a single strain The viscosity was measured by a pipette test. In this test, the flow-out time from a graduated pipette is determined. A longer flow-out time corresponds to a higher viscosity. The curdled milk was prepared from 200 mL of skim milk inoculated with 1% of the bacterial strain to be tested (cultured in skim milk overnight at 37°C) and incubated for 20 hours at 42°C. The viscosity of the curdled milk was measured in a 25 mL graduated pipette and the flow-out time of said curdled milk from the pipette was measured three times. The curdled milk was carefully stirred with a spoon to homogenize it. A 25 mL graduated pipette was then filled and the time it takes for the pipette to empty by gravity was measured. The time in seconds to empty 25 mL of curdled milk from the pipette is given.

[0134] DSM22933 provides higher viscosity than its parent strain DSM22587, as it produces a 25% increase in efflux time as measured by the pipette test shown in the table below.

[0135] [Table 2]

[0136] Example 3: Viscosity pipette test of DSM22933 in mixed cultures Pipette tests were performed as described in Example 2, except that overnight culture and final incubation were performed at 37° C. Fermentations with mixed cultures of 0.9% DSM 22933 or DSM 22587 with 0.1% Lactobacillus delbrueckii subsp. bulgaricus strain DSM 19251 and 1.0% yeast extract were allowed to reach a final pH of 3.8.

[0137] The DSM 22933 strain of the present invention also shows improved viscosity in mixed culture with L. bulgaricus DSM 19251 strain and yeast, as can be seen from the table below.

[0138] [Table 3]

[0139] Example 4: Aspirating mini yoghurts produced with DSM 22933 The mini yoghurts were produced from a milk base containing 4.0% protein and 0.1% fat inoculated with 0.02% F-DVS starter culture. The textural properties of DSM22933 and DSM24023 were evaluated by adding the strains individually to 22 different mixed cultures for comparison. All 22 mixed cultures contained different combinations of S. thermophilus and L. bulgaricus strains. The suction was measured to check the increase in texture. The more negative the suction, the better the texture of the mini yoghurts. The two strains (DSM22933 and DSM24023) are sister strains derived from the same mother strain DSM22587. DSM24023 does not contain the three mutations as described for DSM22933 in Table 1 above.

[0140] Looking at the average of the 22 mini yoghurts, the culture containing DSM 22933 required more pressure to aspirate the yoghurt (-1808 Pa) compared to the culture containing DSM 24023 (-1692 Pa).

[0141] Example 5: Rheological properties of yoghurt produced with DSM 22933 Milk base 1 (MB1) with 3.6% protein and 3% fat or milk base 2 (MB2) with 3.6% protein and 1.5% fat were inoculated with 0.02% FD-DVS starter culture, respectively. Fermentation was carried out at 43°C to pH 4.60. Set yoghurts were stored at 6°C for 7 days. Rheological properties Shear stress were measured on a rheometer (Anton Paar Physica Rheometer with ASC, Automatic Sample Changer, Anton PaarΦ GmbH, Austria) at 13°C with the following settings: - Waiting time (to restore some structure) - 5 minutes without rocking or rotating -Rotation (300s-1 (to measure the shear stress at -Y'=[0.2707-300]s -1 , and y'=[275-0.2707]s -1

[0142] 21 measurement points in 210 seconds (1 point every 10 seconds) for 300 seconds -1 and 0.2707s at 21 measurement points (1 point every 10 seconds) over 210 seconds. -1 For data analysis, the shear rate was 300 s -1 The shear stress at

[0143] Fermentations using cultures containing DSM22933 were compared to fermentations using benchmark cultures containing the prior art strain DSM22589, which does not have the mutations listed above in Table 1. Both cultures contained an additional S. thermophilus strain and a non-texturizing L. bulgaricus strain that were identical in the two cultures.

[0144] Cultures containing DSM22933 show improved viscosity compared to the benchmark as is evident from the two tables below: Results were obtained with 30% DSM22933 compared to 50% DSM22589.

[0145] [Table 4]

[0146] [Table 5]

[0147] Deposits and Specialized Solutions Applicant requests that samples of the deposited microorganisms listed in the table below be made available only to experts approved by Applicant.

[0148] [Table 6]

[0149]

Table 7

[0150] References AgersΦ et al., (2018) Broadbent et al. (2003) J. Dairy Sci., 86:407-423 EMBOSS: The European Molecular Biology Open Software Suite, Rice et al. (2000) Trends in Genetics 16:276-277 Needleman and Wunsch (1970) J. Mol. 25 Biol. 48: 443-453

Claims

1. (i) mutations in the branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) gene; (ii) a mutation in the permease protein gene of an ABC transporter; and / or (iii) a mutation in the peptide deformylase protein gene A Streptococcus thermophilus strain having

2. (i) the mutation in the branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) is a substitution of glutamic acid with valine at a position corresponding to position 169 of SEQ ID NO: 12, and / or a mutation of nucleotide A to nucleotide T at a position corresponding to position 506 of SEQ ID NO: 11; (ii) the mutation in the permease protein of the ABC transporter is a substitution of leucine to phenylalanine at the position corresponding to position 190 of SEQ ID NO:4, and / or a mutation of nucleotide C to nucleotide T at the position corresponding to position 568 of SEQ ID NO:3; and / or 3. The Streptococcus thermophilus strain of claim 1, wherein (iii) the mutation in the peptide deformylase protein is a substitution of arginine with cysteine ​​at a position corresponding to position 144 of SEQ ID NO: 8, and / or a mutation of nucleotide C with nucleotide T at a position corresponding to position 430 of SEQ ID NO:

7.

3. 3. The Streptococcus thermophilus strain according to claim 1, wherein the strain, when used in milk fermentation, produces a higher shear stress and / or a higher efflux time in a viscosity pipette test compared to a strain not having mutations (i), (ii) and / or (iii) as defined in claim 1.

4. 4. The Streptococcus thermophilus strain according to claim 3, wherein the strain is derived from a mother strain that does not have mutations (i), (ii) and / or (iii) as defined in any one of claims 1 or 2.

5. 2. The Streptococcus thermophilus strain of claim 1, wherein the strain is a phage-resistant mutant derived from a strain that does not have mutations (i), (ii) and / or (iii) as defined in any one of claims 1 or 2.

6. 5. The Streptococcus thermophilus strain according to claim 4, wherein the strain not having mutations (i), (ii) and / or (iii) as defined in any one of claims 1 or 2 is strain DSM22587.

7. 6. The Streptococcus thermophilus strain of claim 5, wherein the Streptococcus thermophilus strain is resistant to phage DSM24022.

8. 8. The Streptococcus thermophilus strain of claim 7, wherein the Streptococcus thermophilus strain is DSM22933 or a mutant or variant thereof.

9. 9. The Streptococcus thermophilus strain of claim 8, wherein the mutant or variant exhibits the same or similar texture characteristics as DSM22933.

10. A composition comprising the Streptococcus thermophilus strain of claim 1.

11. A composition comprising the Streptococcus thermophilus strain described in claim 2.

12. A composition comprising the Streptococcus thermophilus strain described in claim 3.

13. A composition comprising the Streptococcus thermophilus strain described in claim 4.

14. A composition comprising the Streptococcus thermophilus strain described in claim 5.

15. A composition comprising the Streptococcus thermophilus strain described in claim 6.

16. A composition comprising the Streptococcus thermophilus strain described in claim 7.

17. A composition comprising the Streptococcus thermophilus strain described in claim 8.

18. A composition comprising the Streptococcus thermophilus strain described in claim 9.

19. A method for producing a fermented product, comprising fermenting a milk substrate with the Streptococcus thermophilus strain according to any one of claims 1 to 2.

20. A fermented product comprising the Streptococcus thermophilus strain described in any one of claims 1 to 2.

21. 15. Fermented product according to claim 14, wherein the product is a dairy product, preferably yogurt, kefir, sour cream, quark or cheese.

22. 1. A method for producing a Streptococcus thermophilus strain that has improved texture characteristics compared to the parent strain when the bacterium is used in milk fermentation, comprising: a) providing a lactic acid bacteria strain as a mother strain; b) exposing the mother strain to a bacteriophage capable of lysing the mother strain; c) isolating mutant strains of the mother strain, wherein the mutant strains are not lysed by the bacteriophage and are: i. Mutations in the branched-chain amino acid transporting ATP-binding protein LivG (TC 3.A.1.4.1) gene; ii. Mutations in the permease protein genes of ABC transporters; iii. Mutations in the peptide deformylase protein gene the above process, wherein the mutant has one, two, or three mutations selected from the group consisting of: d) screening for mutants that exhibit improved texture properties compared to the parent strain when used in milk fermentation The above method, comprising:

23. Use of the Streptococcus thermophilus strain according to any one of claims 1 to 2 for producing a fermented milk product.