Lactic acid bacterium capable of imparting stringiness to food

Abstract

To provide a novel lactic acid bacterium capable of imparting stringiness to a fermented product.SOLUTION: The inventors found that a fermented product with Lactiplantibacillus plantarum KY5-ES5 strain (accession number: NITE P-04000), which is a novel lactic acid bacterium isolated from Japanese pickles, has stringiness. This strain was examined by comparison with JCM1100 strain and JCM1149T strain, which are published strains of Lactiplantibacillus plantarum, and 35 company-owned strains of Lactiplantibacillus plantarum. As a result, it was surprisingly found that only a fermented product obtained by culture with the KY5-ES5 strain exhibits high stringiness. On the basis of this finding, the KY5-ES5 strain was provided as a novel strain.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a novel strain of newly isolated Lactiplantibacillus plantarum, and a food having drawstring properties obtained by culturing the novel strain.

Background Art

[0002] Lactic acid bacteria are known as probiotics that have effects beneficial to intestinal regulation and human health. Lactic acid bacteria are a general term for bacteria that produce lactic acid, and the microbial group called lactic acid bacteria spans many genera and species in taxonomy. Representative lactic acid bacteria include bacteria belonging to the genera Lactobacillus, Lactiplantibacillus, Enterococcus, Lactococcus, Pediococcus, Leuconostoc, Streptococcus, etc. For the classification of such lactic acid bacteria, phylogenetic analysis based on the nucleotide sequences of the 16S rRNA gene and the recA gene is used. The ecology and physiological characteristics of lactic acid bacteria are extremely diverse. Some lactic acid bacteria have been found to exhibit physiological effects such as intestinal regulation, immunomodulatory effects, blood pressure lowering effects, allergy lowering effects, and anti-cholesterol effects in addition to having intestinal regulation effects when administered.

[0003] Lactiplantibacillus plantarum is a Gram-positive bacillus and is known as a lactic acid bacterium often isolated from plant-derived fermentates. There are many salt-tolerant strains, which contribute to the fermentation of pickles, kimchi, sourdough, etc. In addition to pickles, it is also known to be involved in the fermentation of wine, tea leaves (Patent Document 1: JP 2022-073998 A), sausage, and marinated fish roe (Patent Document 2: WO 2020 / 116365). For specific strains of Lactiplantibacillus plantarum, strains having immunomodulatory effects, blood glucose improvement effects, erythropoietin production promotion effects, and lipid reduction effects have been isolated (Patent Document 1: JP 2022-073998 A, Patent Document 2: WO 2020 / 116365, Patent Document 3: JP 2023-507895 T, Patent Document 4: JP 2020-132561 A). Using such functional lactic acid bacteria, products such as pickles, dairy products such as yogurt and cheese, and further supplements or pharmaceuticals containing lactic acid bacteria have been developed.

[0004] In addition, lactic acid bacteria change the physical properties of the fermentation product by culturing. Fermented milk products such as yogurt and cheese have been traditionally produced by fermenting milk with lactic acid bacteria, and lactic acid bacteria that provide a fermentation product with high drawability are also known. Lactococcus lactis subsp. cremoris is known as a lactic acid bacterium that produces a fermentation product with drawability. Lactic acid bacteria that impart drawability usually produce a large amount of exopolysaccharide (EPS), thereby imparting high drawability to the fermentation product (Patent Document 5: JP 2019-198270 A, Patent Document 6: JP 2016-182049 A, Patent Document 7: JP 2016-178911 A, Non-Patent Document 1: Food Bioscience 55 (2023) 103026). As a fermentation product fermented with this lactic acid bacterium, Caspian Sea yogurt, which has been traditionally eaten in the Caucasus region, is known. Caspian Sea yogurt has high drawability and provides a unique texture. On the other hand, since this lactic acid bacterium has poor growth properties in an acidic environment, co-culture with acetic acid bacteria that consume the produced lactic acid is carried out, which makes it difficult to manage the culture and results in a low acidity of the fermentation product. Lactic acid bacteria that impart drawability to the fermentation product without relying on exopolysaccharide are also known, and drawability is generated by the action of protease produced by the lactic acid bacterium on the protein of the culture raw material (Patent Document 8: JP 2022-026233 A). Foods with high drawability have a texture such as smoothness. This enables the development of products with a unique texture.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0006] [Non-Patent Document 1] Food Bioscience 55 (2023)103026 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] An object of the present invention is to provide a new lactic acid bacterium capable of imparting drawability to a fermented product. [Means for Solving the Problems]

[0008] The present inventors have found that a fermented product of Lactiplantibacillus plantarum KY5-ES5 strain (Accession No.: NITE P-04000), which is a novel lactic acid bacterium isolated from pickles, has drawability. When compared with the publicly available strains JCM1100 and JCM1149T of Lactiplantibacillus plantarum, and 35 strains of the same species owned by the company, surprisingly, it was found that only the fermented product cultured with the KY5-ES5 strain has high drawability, and the KY5-ES5 strain is provided as a novel strain.

[0009] Therefore, the present invention relates to the following inventions: [1] A lactic acid bacterium that is Lactiplantibacillus plantarum with the accession number NITE P-04000. [2] A culture containing the lactic acid bacterium according to item 1. [3] The culture according to item 2 having stringiness. [4] The culture according to item 3, wherein the culture is fermented soy milk or fermented milk. [5] A food containing the lactic acid bacterium according to item 1 and its culture. [6] A starter culture containing the lactic acid bacterium according to item 1 or its culture. [7] A method for producing a fermented food having stringiness, comprising: inoculating a food raw material with a lactic acid bacterium which is Lactiplantibacillus plantarum with the accession number: NITE P-04000; the production method including a step of culturing at 15°C to 30°C.

Effect of the Invention

[0010] The lactic acid bacterium of the present invention provides high stringiness in the fermented product.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0012] The present invention relates to a novel strain of isolated lactic acid bacterium, KY5-ES5 strain (Accession No.: NITE P-04000), belonging to Lactiplantibacillus plantarum. This strain was screened, isolated, and selected from 20 types of pickles from various regions of Japan, and is one of the selected strains. This strain has been determined to belong to Lactiplantibacillus plantarum by phylogenetic analysis based on the nucleotide sequences of the 16S rRNA gene and recA gene. The lactic acid bacterium of the present invention includes the strain deposited under the accession number: NITE P-04000, as well as progeny strains or mutant strains of the strain capable of conferring flocculability equivalent to that of the strain.

[0013] When soymilk is fermented under predetermined conditions using the strain according to the present invention, it has stringiness. When cultured at 37°C, stringiness was not observed, while stringiness was observed when cultured at 30°C, 25°C, and 20°C. The lower the culture temperature, the higher the stringiness of the fermented product. Therefore, after seeding, the strain of the present invention is preferably cultured at 30°C or lower, preferably 25°C or lower, and more preferably 20°C or lower. The lower limit of the culture temperature is not particularly limited, but from the viewpoint of the fermentation rate, 12°C or higher, preferably 15°C or higher, more preferably 18°C or higher, and still more preferably 20°C or higher is used. In addition, the stringiness in the fermented product of this strain has the characteristic that it disappears when the temperature rises, and when heated at 37°C or higher, the stringiness is irreversibly lost (Figure 6). Since the fluidity of the fermented product increases when the stringiness is lost, it becomes possible to produce fermented foods and beverages with the same taste and aroma but different fluidity, i.e., thickness and smoothness, by heating treatment after fermentation, and it is possible to meet various needs of consumers. Also, due to this characteristic, it can also be used for quality control in the cold chain. That is, since the stringiness is lost when placed under high-temperature conditions during transportation or storage, the quality control of low-temperature transportation and low-temperature storage can be evaluated by measuring the stringiness.

[0014] Stringiness means the property of stretching like a thread that appears when the viscosity of a liquid is high. Stringiness is not determined only by viscosity, but is a property affected by surface tension as well as viscosity. In the present invention, stringiness can be measured using a Zahn cup. The Zahn cup has holes, and by measuring the time it takes to flow out from the holes, the stringiness can be measured. The pore diameter of the holes can be selected according to the measurement object. As an example, a Zahn cup with a pore diameter of 7 mm can be used, and when the viscosity is low, a Zahn cup with a smaller pore diameter, such as 5 mm or 2 mm, can be used.

[0015] Due to the stringiness, the culture fermented by the lactic acid bacteria according to the present invention can provide a smooth and mellow taste. Such properties contribute to the development of products that can provide a new texture during beverage development. Also, not only beverages but also solid substances can be provided with a new texture.

[0016] The present invention relates to a culture cultivated by the lactic acid bacteria according to the present invention. The culture can be obtained by inoculating and culturing the lactic acid bacteria according to the present invention on any food raw material. In the present invention, culturing and fermentation can be used interchangeably, and the culture and the fermented product can also be used interchangeably. The culture thus obtained may contain lactic acid bacteria, products of lactic acid bacteria, and substances derived from the culture medium and food raw materials. Substances derived from food raw materials can be altered by lactic acid bacteria and enzymes produced by lactic acid bacteria.

[0017] The lactic acid bacteria according to the present invention were shown to have high stringiness when cultured in a protein-containing synthetic medium and when fermenting milk and soy milk (Figs. 2 to 4). Also, stringiness was observed even when cultured in a protein-free medium, although the degree was low (Fig. 5). Although not intended to be limited by theory, the stringiness is thought to be due to the interaction between extracellular polysaccharide and protein, and it is considered that the lactic acid bacteria according to the present invention secrete an amount of protein sufficient to cause stringiness even in a protein-free medium. That is, according to the lactic acid bacteria of the present invention, it is considered that stringiness can be caused using only a trace amount of protein contained in the protein-free medium.

[0018] The food raw materials fermented by lactic acid bacteria according to the present invention are roughly classified into raw materials containing animal proteins and raw materials containing plant proteins and other proteins. Examples of raw materials containing animal proteins include milk, gravy, cell extracts, meat, fish, etc. Examples of raw materials containing plant proteins include plant bodies, plant juices, plant extracts, etc. Examples of other proteins include proteins derived from microorganisms, such as yeast extracts. The plant from which the plant juice and plant extract are derived may be any plant, and as an example, soybean extract, especially soy milk, can be mentioned. The food raw material may be liquid, solid, or a liquid containing solids. By inoculating these raw materials with lactic acid bacteria, fermented vegetable products, fermented dairy products, fermented fish products, fermented meat products, fermented seasonings, fermented beverages, etc. are provided. From the viewpoint of exhibiting drawability, the fermented product is preferably a liquid fermented product, but even a solid fermented product can be given a smooth texture if the liquid contained in the solid fermented product has drawability.

[0019] As an example of the fermented vegetable product, pickles can be mentioned. Among pickles, fermented pickles fermented by adding the lactic acid bacteria according to the present invention are preferred, but pickles that are not fermented, such as light pickles and vinegar pickles, may also be used. Examples of fermented dairy products include cheese, yogurt, butter, etc. Examples of fermented beverages include fermented milk, fermented soy milk, etc.

[0020] As food ingredients for pickles, any vegetables commonly used in commercially available pickles can be used, including eggplant, daikon radish, turnip, carrot, ginger, myoga, cucumber, bitter gourd, green pepper, chili pepper, Chinese cabbage, aona, takana, nozawana, nishin-sai, perilla, garlic, tomato, burdock, rice, beans, bran, etc., but it is not intended to be limited to these. These vegetables are usually washed and then subjected to pickling treatment with a seasoning containing salt, and then the lactic acid bacteria of the present invention are added for fermentation treatment. The pickling treatment and the fermentation treatment can be appropriately selected according to the target pickle product. As the fermentation treatment, additives can be optionally added and fermented together with the target vegetables. Such additives can include bran, rice bran, kelp, chili pepper, dried tangerine peel, etc. As food ingredients, in addition to the above-mentioned vegetables, raw milk, processed milk, soybeans, rice, bran, etc. are used.

[0021] The culture of lactic acid bacteria in the present invention is, for example, a culture solution obtained by culturing lactic acid bacteria in a medium. The culture may contain lactic acid bacteria and / or their dead cells. The culture is obtained by culturing lactic acid bacteria by a known method. Media commonly used for culturing lactic acid bacteria, such as MRS medium, BCP medium, etc., can be used, and an appropriate pH, for example, 3 to 8, preferably 4 to 7, can be selected according to the lactic acid bacterial strain. A solid medium may be used for isolation and preservation of the strain, or a liquid medium may also be used. The culture can be carried out at 15 to 45°C, preferably 18 to 40°C, more preferably 20 to 37°C, under anaerobic or aerobic conditions (Figure 1). Centrifugation can be applied to the culture to collect lactic acid bacteria.

[0022] In another aspect of the invention, it relates to a starter culture containing lactic acid bacteria of the KY5-ES5 strain (deposit number: NITE P-04000) or a culture thereof. A starter culture refers to lactic acid bacteria or a culture thereof used to promote fermentation in a specific flora. The starter culture may be a freeze-dried powder of a culture of isolated and cultured lactic acid bacteria or cells collected from the culture, or it may be a culture containing lactic acid bacteria or a frozen product thereof. Examples of the starter culture include dried cells and koji beds. Before being added to food raw materials, preculture may be performed to use the culture in the logarithmic growth phase as the starter culture.

[0023] In one aspect of the present invention, it also relates to a method for producing a fermented food, which includes the step of inoculating a food raw material with the lactic acid bacteria or a culture thereof according to the present invention. The lactic acid bacteria or a culture thereof may be added as a starter culture, or may be added as a part of a separately produced fermented product. After the lactic acid bacteria or a culture thereof comes into contact with the food raw material, a fermentation step is carried out. Here, contact includes adding the lactic acid bacteria or a culture thereof to the food raw material and adding the food raw material to the lactic acid bacteria or a culture thereof, and further mixing may be performed. The fermentation step may be carried out under appropriate temperature control or at the temperature of the surrounding environment. From the viewpoint of exhibiting drawability, it is preferably cultured at 30°C or lower, more preferably at 25°C or lower, and even more preferably at 20°C or lower. The lower limit of the temperature may be appropriately selected according to the temperature at which fermentation occurs, and usually 12°C or higher, preferably 15°C or higher can be used. The fermentation period is appropriately selected according to the type of food so as to exhibit a good taste.

[0024] More specifically, it is a method for producing fermented soy milk having drawability Inoculate the fermented soy milk with lactic acid bacteria, which is Lactiplantibacillus plantarum with the deposit number: NITE P-04000; The manufacturing method includes a step of culturing at 15°C to 30°C, more preferably 25°C or lower, and even more preferably 20°C or lower. When manufacturing fermented soy milk, the lower the culturing temperature, the higher the drawability can be imparted (Figure 1). The fermentation temperature can also be selected as 20°C, 18°C, or 16°C.

[0025] As yet another specific example, a method for manufacturing fermented milk having drawability, inoculate milk with a lactic acid bacterium that is Lactiplantibacillus plantarum with the accession number: NITE P-04000; The manufacturing method includes a step of culturing at 20°C to 45°C, more preferably 40°C or lower, and even more preferably 37°C or lower. The fermented milk thus obtained, that is, yogurt, has high drawability even when cultured at 30°C.

[0026] A mutant strain refers to a strain to which artificial or accidental mutations have been added to an isolated strain. Mutant strains can occur naturally by subculturing an isolated strain, and examples include chemical treatments using mutagens, such as chemicals that cause mutations, and physical treatments such as irradiation with ultraviolet rays, X-rays, gamma rays, etc. As chemical treatments, in addition to substances that act on nucleic acids to cause mutations, such as nitrous acid, hydroxylamine, acridine, base analogs such as 5-bromouracil, 2-aminopurine, etc. are used.

[0027] All documents mentioned in this specification are hereby incorporated by reference in their entirety into this specification.

[0028] The examples of the present invention described below are for illustrative purposes only and do not limit the technical scope of the present invention. The technical scope of the present invention is limited only by the description in the claims. Changes to the present invention, such as addition, deletion, and substitution of the constituent elements of the present invention, can be made on the condition that the gist of the present invention is not deviated from.

Examples

[0029] Example 1: Screening Twenty samples of fermented pickles collected from various regions across the country were gathered. Specifically, 3 samples of Akita iburi pickled turnips, 3 samples of Nagano Nozawana pickles, 3 samples of Aichi pickled turnips, 1 sample of Yamagata pesora pickles, 1 sample of Nara pickled cucumber in bran, 4 samples of Kyoto shiba pickles, 3 samples of Hiroshima vegetables from Hiroshima, and 2 samples of Fukuoka takana pickles were collected. The cleaning solution obtained by washing the fermented pickles was smeared on an MRS (manufactured by Becton Dickinson) plate medium and cultured anaerobically at 30 °C or 37 °C for 24 hours or more. Using 10 - 20 colonies per plate medium as a guide, colonies were picked with a sterilized toothpick, and the stringiness was visually evaluated. Fifty-six colonies showing stringiness were selected and inoculated onto a new MRS plate medium. Then, it was cultured anaerobically at the same culture temperature (30 °C or 37 °C) for 24 hours again, the bacterial cells were picked with a platinum loop, and the stringiness was evaluated again. One strain of the colony showing the strongest stringiness among these was selected and designated as KY5-ES5.

[0030] The glycerol stock of the isolated bacteria was smeared on an MRS plate medium and cultured anaerobically at 37 °C overnight using an AnaeroPack. One platinum loopful of the obtained bacterial cells was inoculated into 7 mL of MRS liquid medium in a 7 mL screw-cap test tube and cultured statically at 37 °C for 24 hours. 1 mL of the obtained culture solution was centrifuged at 6000 xg, 20 °C for 5 minutes to recover the bacterial cells. The obtained bacterial cells were resuspended in sterilized water, and DNA was extracted using the Quick-DNA Fungal / Bacterial Kit Miniprep (manufactured by Zymoresearch). Using the obtained DNA as a template, DNA fragments were obtained by the PCR method using the following primers that amplify the 16S rRNA gene and the recA gene region. [Table 1] The nucleotide sequence of the obtained DNA fragment was determined. Among the obtained nucleotide sequences, the portions with a quality score of 40 or higher in the sequencing results were excised and used for subsequent analysis. From the sequence information, sequence analysis of the 16S rRNA and recA genes was performed to identify the type of bacterium, and it was found to be Lactiplantibacillus plantarum. The KY5-ES5 strain was deposited at the Patent Microorganisms Depositary, National Institute of Technology and Evaluation (NPMD) (2-5-8 Kazusa Kamatari, Kisarazu, Chiba) (Accession No.: NITE P-04000, Date of Deposit: October 25, 2023). In addition, the recA gene sequences of the strains listed in Fig. 7 were downloaded from the database GenBank provided by the National Center for Biotechnology Information of the United States for phylogenetic analysis. The nucleotide sequences of the recA genes of all the strains to be analyzed were aligned using MAFFT. The aligned nucleotide sequences were converted into the PHYLIP format, and a phylogenetic tree was estimated using RAxML. The estimation results were visualized using FigTree to obtain a phylogenetic tree diagram (Fig. 7).

[0031] Since the KY5-ES5 strain was Lactiplantibacillus plantarum, glycerol stocks of 38 strains including 35 strains of Lactiplantibacillus plantarum owned by the company and 2 commonly available strains (JCM1100 strain and JCM1149T: RIKEN) were streaked on MRS agar plates and anaerobically cultured at 37°C overnight using an AnaeroPack. One platinum loopful of the obtained cells was inoculated into 7 mL of MRS liquid medium in a 7 mL screw-cap test tube and statically cultured at 37°C for 24 hours. The turbidity (OD) of the obtained culture broth was measured at a wavelength of 600 nm, and the culture broth was inoculated into 40 mL of unprepared soy milk (manufactured by Kikkoman) in a 50 mL centrifuge tube so that the OD was 0.1. It was statically cultured at 30°C or 20°C for 24 hours. After the fermentation was completed, the obtained solid matter was stirred 10 times with a medicine spoon to make it uniform over the entire centrifuge tube, and then the operation of scooping up the solid matter with a medicine spoon and pouring it out was performed to qualitatively visually evaluate the stringiness of the fermented soy milk. The results are shown below:

Table 2

[0032] Example 2: Growth evaluation of KY5-ES5 strain The glycerol stock of the isolated KY5-ES5 strain was spread on MRS plate medium and anaerobically cultured at 37°C overnight using an AnaeroPack. One platinum loopful of the obtained cells was inoculated into 7 mL of MRS liquid medium in a 7 mL screw-cap test tube and statically cultured at 37°C for 24 hours. The cells were collected from the obtained culture solution by centrifugation at 6000 x g, 20°C for 5 minutes. The cells were washed twice with sterile physiological saline. The OD of the obtained bacterial solution was measured (wavelength 600 nm), and inoculated into 15 mL of MRS liquid medium in a 15 mL screw-cap test tube so that the OD600 was 0.01. Static culture was performed at each culture temperature of 42°C, 37°C, 30°C, 25°C, and 20°C. The results are shown in Figure 1.

[0033] Example 3: Quantitative comparison of drawability of fermented soy milk by KY5-ES5 strain Glycerol stocks of Lactiplantibacillus plantarum JCM1100 strain, JCM1149T strain, and KY5-ES5 strain were streaked on MRS agar plates and anaerobically cultured overnight at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) using an AnaeroPack. One platinum loopful of the obtained cells was inoculated into 7 mL of MRS liquid medium in a 7-mL screw-cap test tube and statically cultured at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) for 24 hours. The OD (wavelength 600 nm) of the obtained culture broth was measured, and the culture broth was inoculated into 200 mL of unprepared soy milk (manufactured by Kikkoman) in a 200-mL beaker so that the OD became 0.1. Anaerobic static culture was performed at 37 °C, 30 °C, 25 °C, or 20 °C for 16 hours or 24 hours using an AnaeroPack. After fermentation, it was stored at 4 °C for 3 hours or more to stabilize the temperature. While maintaining the temperature on ice, the entire container was stirred 10 times with a medicine spoon to make it uniform. The sample was placed in a Zahn cup type 417 No. 7 (manufactured by Rika Shokai Co., Ltd.), and the time (in seconds) from when the hole at the bottom was opened and the sample separated until the outflow of the fermented soy milk stopped was measured. However, if the fluidity of the sample was extremely low and the outflow did not start immediately after the sample separated from the bottom, it was regarded as "not discharging". The results are shown in Fig. 2. The fermented product of the KY5-ES5 strain showed no drawability when fermented at 37 °C, while the drawability increased as the culture temperature decreased.

[0034] Example 4: Quantitative comparison of the drawability of fermented milk Glycerol stocks of Lactiplantibacillus plantarum JCM1100 strain, JCM1149T strain, and KY5-ES5 strain were streaked on MRS agar plates and cultured anaerobically overnight at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) using an AnaeroPack. One platinum loopful of the obtained cells was inoculated into 7 mL of MRS liquid medium in a 7 mL screw-cap test tube and statically cultured at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) for 24 hours. The OD (wavelength 600 nm) of the obtained culture broth was measured, and the culture broth was inoculated into 200 mL of unadjusted milk (manufactured by Meiji Co., Ltd.) in a 200 mL beaker so that the OD became 0.6. Static anaerobic culture was performed at 30 °C or 20 °C for 24 hours using an AnaeroPack. After the fermentation was completed, it was stored at 4 °C for 3 hours or more to stabilize the temperature. While maintaining the temperature on ice, the entire container was stirred 10 times with a medicine spoon to make it uniform. The sample was placed in a Zahn cup type 417 No. 7 (manufactured by Rika Co., Ltd.), and the time (in seconds) until the fermented milk flowed out from the hole opened at the bottom and stopped was measured. The results are shown in Fig. 3. The fermented milk fermented with the KY5-ES5 strain had high stringiness even when fermented at 30 °C.

[0035] Example 5: Quantitative comparison of stringiness in MRS medium Glycerol stocks of Lactiplantibacillus plantarum JCM1100 strain, JCM1149T strain, and KY5-ES5 strain were streaked on MRS agar plates and anaerobically cultured overnight at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) using an AnaeroPack. One platinum loopful of the obtained cells was inoculated into 7 mL of MRS liquid medium in a 7 mL screw-cap test tube and statically cultured at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) for 24 hours. Cells were recovered from the obtained culture broth by centrifugation at 6000 xg, 20 °C for 5 minutes and washed twice with sterilized physiological saline. The OD of the obtained cell suspension was measured (wavelength 600 nm), and the culture broth was inoculated into 100 mL of MRS liquid medium in a 100 mL Erlenmeyer flask so that the OD became 0.01. The mixture was statically cultured at 37 °C, 30 °C or 25 °C for 24 hours, or at 20 °C for 48 hours. After completion of the culture, the mixture was placed in a water bath set at 25 °C for 10 minutes or more to stabilize the temperature. The sample was placed in a Zahn cup type 417 No. 7 (manufactured by Rika Kogyo Co., Ltd.), and the time (in seconds) until the medium flowed out through the hole opened at the bottom and became interrupted was measured. The results are shown in Fig. 4. The MRS medium containing the protein fermented by the KY5-ES5 strain had low drawability when fermented at 37 °C, and the drawability increased as the temperature decreased.

[0036] Example 6: Quantitative comparison of drawability in protein-free synthetic medium Glycerol stocks of Lactiplantibacillus plantarum JCM1100 strain, JCM1149T strain, and KY5-ES5 strain were streaked on MRS agar plates and cultured anaerobically at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) overnight using an AnaeroPack. One platinum loopful of the obtained cells was inoculated into 7 mL of MRS liquid medium in a 7-mL screw-cap test tube and statically cultured at 30 °C (JCM1149T strain) or 37 °C (JCM1100 strain, KY5-ES5 strain) for 24 hours. Cells were recovered from the obtained culture broth by centrifugation at 6000 xg, 20 °C for 5 minutes and washed twice with sterile physiological saline. As a synthetic medium, LABMM80 containing Tween 80 as a surfactant was used (Table 3). The OD of the obtained bacterial solution was measured (wavelength 600 nm), and the culture broth was inoculated into 100 mL of synthetic medium in a 100-mL Erlenmeyer flask so that the OD became 0.1. The mixture was statically cultured at 30 °C for 24 hours. After the culture was completed, it was placed in a water bath set at 25 °C for 10 minutes or more to stabilize the temperature. The sample was placed in a Zahn cup type 417 No. 2 (manufactured by Reika Co., Ltd.), and the time (in seconds) until the medium flowed out through the hole opened at the bottom and became interrupted was measured. The results are shown in Fig. 5. The drawability of the protein-free LABMM80 medium fermented with the KY5-ES5 strain was low, drawability could be measured using a Zahn cup type 417 No. 2, and the drawability was increased by using this strain.

Table 3

[0037] Example 7: Thermal stability of drawability The glycerol stock of Lactiplantibacillus plantarum KY5-ES5 strain was streaked on MRS agar plate and anaerobically cultured at 37 °C overnight using an AnaeroPack. One platinum loopful of the obtained cells was inoculated into 7 mL of MRS liquid medium in a 7 mL screw-cap test tube and statically cultured at 37 °C for 24 hours. The cells were recovered from the obtained culture broth by centrifugation at 6000 x g, 20 °C for 5 minutes, and washed twice with sterilized physiological saline. The OD of the obtained cell suspension was measured (wavelength 600 nm), and the culture broth was inoculated into 500 mL of MRS liquid medium in a 500 mL Erlenmeyer flask so that the OD became 0.01. The culture was statically incubated at 20 °C for 48 hours. After the culture was completed, the culture broth was divided into two parts. One part was kept warm at 20 °C, and the other part was placed in a water bath set at 25 °C for 10 minutes or more to stabilize the temperature. The sample was put into a Zahn cup type 417 No. 7 (manufactured by Rika Kogyo Co., Ltd.), and the time (seconds) until the medium flowed out from the hole opened at the bottom and stopped was measured. This was taken as the value at 0 minutes of heating. The culture broth measured at 0 minutes of heating was placed in a water bath set at 37 °C, and the heating time was measured starting from the point when the culture broth temperature reached 37 °C. When 10 minutes, 20 minutes, 30 minutes, and 40 minutes of heating time had elapsed, the culture broth was taken out separately and placed in a 25 °C water bath to stabilize the temperature. When the sample heated for 40 minutes was obtained, the culture broth kept warm at 20 °C was also placed in a 25 °C water bath at the same time to stabilize the temperature. This sample was used as the 20 °C 40-minute holding sample. When the temperature was stabilized, the sample was put into a Zahn cup type 417 No. 7 (manufactured by Rika Kogyo Co., Ltd.), and the time (seconds) until the medium flowed out from the hole opened at the bottom and stopped was measured. The results are shown in Fig. 6.

Deposit Number

[0038] NITE P-04000

Claims

1. A lactic acid bacterium which is Lactiplantibacillus plantarum with the deposit number NITE P - 04000.

2. A culture containing the lactic acid bacterium according to Claim 1.

3. The culture according to Claim 2, having stringiness.

4. The culture according to Claim 3, wherein the culture is fermented soy milk or fermented milk.

5. A food containing the lactic acid bacterium according to Claim 1 and its culture.

6. A starter culture containing the lactic acid bacterium according to Claim 1 or its culture.

7. A method for producing a fermented food having stringiness, comprising: inoculating a food raw material with a lactic acid bacterium which is Lactiplantibacillus plantarum with the deposit number NITE P - 04000; culturing at 15°C to 30°C.

Images