Lactic acid bacterium capable of imparting stringiness to food

Abstract

[PROBLEM] To provide a novel lactic acid bacterium capable of imparting stringiness to a fermented product. [Solution] In the present invention, it is 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 is 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 is surprisingly found that only a fermented product obtained by the culture with the KY5-ES5 strain exhibits high stringiness. On the basis of this finding, the KY5-ES5 strain is provided as a novel strain.

Description

Lactic acid bacteria that impart spinnability to foods

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

[0002] Lactic acid bacteria are known as probiotics that regulate the intestines and have beneficial effects on human health. Lactic acid bacteria is a general term for bacteria that produce lactic acid, and the microorganisms known as lactic acid bacteria span numerous genera and species. Representative lactic acid bacteria include bacteria belonging to the genera Lactobacillus, Lactipruntibacillus, Enterococcus, Lactococcus, Pediococcus, Leuconostoc, and Streptococcus. Phylogenetic analysis based on the base sequences of the 16S rRNA gene and recA gene is used to classify these lactic acid bacteria. The ecological and physiological characteristics of lactic acid bacteria are extremely diverse. Some lactic acid bacteria have been found to exert physiological effects such as immunoregulatory effects, blood pressure lowering effects, allergy-reducing effects, and cholesterol-lowering effects when administered, in addition to regulating the intestines.

[0003] Lactiplantibacillus plantarum is a gram-positive bacillus known as a lactic acid bacterium that is often isolated from plant-derived fermented products. Many strains are salt-tolerant and contribute to the fermentation of pickled vegetables, kimchi, sauerkraut, and other foods. It is also known to be involved in the fermentation of wine, tea leaves (Patent Document 1: JP 2022-073998 A), sausages, and funazushi (Patent Document 2: WO 2020 / 116365 A). Regarding specific strains of Lactiplantibacillus plantarum, strains having immunomodulatory effects, blood sugar improving effects, erythropoietin production promoting effects, and lipid-reducing effects have been isolated (Patent Document 1: JP 2022-073998 A, Patent Document 2: WO 2020 / 116365 A, Patent Document 3: JP 2023-507895 A, Patent Document 4: JP 2020-132561 A). Using lactic acid bacteria with such functionality, pickles, dairy products such as yogurt and cheese, and even supplements or pharmaceuticals containing lactic acid bacteria have been developed.

[0004] Furthermore, lactic acid bacteria change the physical properties of fermented products when cultured. Fermented dairy products such as yogurt and cheese have traditionally been produced by fermenting milk with lactic acid bacteria, and lactic acid bacteria that produce fermented products with high spinnability are also known. Lactococcus lactis subsp. cremoris is known as a lactic acid bacterium that produces fermented products with spinnability. Lactic acid bacteria that impart spinnability typically produce large amounts of exopolysaccharides (EPS), thereby imparting high spinnability to the fermented 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). Caspian Sea yogurt, traditionally eaten in the Caucasus, is a known fermented product fermented with this lactic acid bacterium. Caspian Sea yogurt has high spinnability and provides a unique texture. However, because this lactic acid bacterium does not grow well in acidic environments, it is cultured in combination with acetic acid bacteria, which consume the lactic acid produced. This makes culture management difficult and results in a low sourness in the fermented product. Lactic acid bacteria that impart spinnability to fermented products without relying on exopolysaccharides are also known, and spinnability occurs when proteases produced by the lactic acid bacterium act on proteins in the culture material (Patent Document 8: JP 2022-026233 A). Foods with high spinnability have textures such as smoothness. This makes it possible to develop products with unique textures.

[0005] Japanese Patent Application Laid-Open No. 2022-073998 International Publication No. 2020 / 116365 Japanese Patent Application Laid-Open No. 2023-507895 Japanese Patent Application Laid-Open No. 2020-132561 Japanese Patent Application Laid-Open No. 2019-198270 Japanese Patent Application Laid-Open No. 2016-182049 Japanese Patent Application Laid-Open No. 2016-178911 Japanese Patent Application Laid-Open No. 2022-026233

[0006] Food Bioscience 55 (2023)103026

[0007] The purpose of the present invention is to provide a new lactic acid bacterium that can impart spinnability to fermented products.

[0008] The present inventors have discovered that the fermentation product of Lactiplantibacillus plantarum strain KY5-ES5 (accession number: NITE P-04000), a novel lactic acid bacterium isolated from pickles, has spinnability. After comparative studies with publicly available Lactiplantibacillus plantarum strains JCM1100 and JCM1149T, as well as 35 in-house strains of the same species, the present inventors have surprisingly found that only the fermentation product cultured with strain KY5-ES5 has high spinnability, and thus present strain KY5-ES5 as a novel strain.

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

[0010] The lactic acid bacteria of the present invention provide high spinnability in the fermented product.

[0011] Figure 1 is a graph showing the results of examining the growth of the KY5-ES5 strain in MSR medium at various fermentation temperatures. Figure 2 is a graph showing the difference in spinnability of fermented soy milk fermented at various fermentation temperatures using the KY5-ES5 strain, the JCM1100 strain, and the JCM1149T strain (A: 16-hour culture, B: 24-hour culture). Figure 3 is a graph showing the difference in spinnability of fermented milk (yogurt) fermented at various fermentation temperatures using the KY5-ES5 strain, the JCM1100 strain, and the JCM1149T strain (B: 24-hour culture). Figure 4 is a graph showing the difference in spinnability of fermented soy milk fermented at various fermentation temperatures using the KY5-ES5 strain, the JCM1100 strain, and the JCM1149T strain (C: 24-hour culture). Figure 5 is a graph showing the change in spinnability when the KY5-ES5 strain, JCM1100 strain, and JCM1149T strain were cultured in a protein-free synthetic medium at 30°C. Figure 6 is a graph showing the change in spinnability of the KY5-ES5 strain fermentation product with temperature. Figure 7 shows the results of a phylogenetic analysis of the KY5-ES5 strain and related strains.

[0012] The present invention relates to strain KY5-ES5 (Accession Number: NITE P-04000), a novel strain of lactic acid bacteria belonging to the genus Lactiplantibacillus plantarum. This strain was one of the strains screened, isolated, and selected from 20 types of pickles grown throughout Japan. 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 bacteria of the present invention include the strain deposited under Accession Number: NITE P-04000, as well as progeny or mutant strains of this strain that can confer spinnability equivalent to that of this strain.

[0013] When soy milk is fermented under specified conditions using the strain of the present invention, it exhibits spinnability. While no spinnability was observed when cultured at 37°C, spinnability was observed when cultured at 30°C, 25°C, and 20°C. The lower the culture temperature, the higher the spinnability of the fermented product. Therefore, after inoculation, the strain of the present invention is preferably cultured at 30°C or below, preferably 25°C or below, and even more preferably 20°C or below. While there are no particular restrictions on the lower limit of the culture temperature, from the viewpoint of fermentation rate, a temperature of 12°C or above, preferably 15°C or above, more preferably 18°C ​​or above, and even more preferably 20°C or above is used. Furthermore, the spinnability of the fermented product of this strain is characterized by disappearing at higher temperatures, and is irreversibly lost when heated to 37°C or above ( FIG. 6 ). Since the loss of spinnability increases the fluidity of the fermented product, it is possible to produce fermented foods and beverages with the same taste and aroma that differ only in fluidity, i.e., thickness and texture, by heating after fermentation, thereby meeting diverse consumer needs. This characteristic also makes it possible to use it for quality control in the cold chain. That is, since spinnability is lost when exposed to high temperatures during transportation and storage, measuring spinnability can be used to evaluate quality control during low-temperature transportation and storage.

[0014] Spinnability refers to the property of stretching like a thread, which appears when the viscosity of a liquid is high. Spinnability is not determined solely by viscosity, but is a property that is influenced by viscosity as well as surface tension. In the present invention, spinnability can be measured using a Zahn cup. The Zahn cup has holes, and spinnability can be measured by measuring the time it takes for the liquid to flow out of the holes. The hole size can be selected depending on the object to be measured. For example, a Zahn cup with a hole size of 7 mm can be used, and when the viscosity is low, a Zahn cup with a smaller hole size, such as 5 mm or 2 mm, can be used.

[0015] Due to the spinnability, the culture fermented with the lactic acid bacteria of the present invention can provide a thick and smooth mouthfeel. This property contributes to the development of products that can provide new textures when developing beverages. Furthermore, it can provide new textures not only to beverages but also to solid objects.

[0016] The present invention relates to a culture cultivated by the lactic acid bacteria of the present invention. A culture can be obtained by inoculating any food material with the lactic acid bacteria of the present invention and culturing it. In the present invention, the terms "cultivation" and "fermentation" can be used interchangeably, and the terms "culture" and "fermented product" can also be used interchangeably. The culture thus obtained can contain lactic acid bacteria, products of the lactic acid bacteria, and substances derived from the medium or food material. Substances derived from the food material can be altered by the lactic acid bacteria and enzymes produced by the lactic acid bacteria.

[0017] The lactic acid bacteria of the present invention were shown to have high spinnability when cultured in a protein-containing synthetic medium and when fermenting milk or soy milk (Figures 2 to 4). Furthermore, spinnability was observed, albeit to a lesser extent, when cultured in a protein-free medium (Figure 5). Without intending to be limited by theory, spinnability is due to the interaction between exopolysaccharides and proteins, and the lactic acid bacteria of the present invention are thought to secrete proteins in amounts sufficient to induce spinnability even in a protein-free medium. In other words, it is believed that the lactic acid bacteria of the present invention can induce spinnability using only trace amounts of protein contained in a protein-free medium.

[0018] Food ingredients fermented by the lactic acid bacteria of the present invention can be broadly divided into ingredients containing animal protein and ingredients containing plant protein or other proteins. Examples of ingredients containing animal protein include milk, meat juice, cell extracts, meat, and fish. Examples of ingredients containing plant protein include plants, plant juice, and plant extracts. Examples of other proteins include proteins derived from microorganisms, such as yeast extract. The plant juice and plant extract may be derived from any plant, but an example is soy extract, particularly soy milk. Food ingredients may be liquid, solid, or liquid containing solids. Inoculating these ingredients with lactic acid bacteria can produce fermented vegetable products, fermented dairy products, fermented fish products, fermented meat products, fermented seasonings, fermented beverages, and the like. From the perspective of exhibiting spinnability, liquid fermentation is preferred. However, the spinnability of the liquid contained in the solid fermentation product can also impart a smooth texture to the solid fermentation product.

[0019] An example of a fermented vegetable product is pickles. Among pickles, fermented pickles fermented with the addition of the lactic acid bacteria of the present invention are preferred, but non-fermented pickles such as lightly pickled or vinegared pickles may also be used. Examples of fermented dairy products include cheese, yogurt, and butter. Examples of fermented beverages include fermented milk and fermented soy milk.

[0020] Food ingredients used for pickles include any vegetables commonly used in commercially available pickles, such as eggplant, radish, turnip, carrot, ginger, myoga, cucumber, bitter melon, bell pepper, chili pepper, Chinese cabbage, green onion, mustard greens, mustard greens, nozawana (green mustard greens), mibuna (green mustard greens), shiso (perilla), garlic, tomato, burdock, rice, beans, and bran. These vegetables are typically washed and then pre-pickled in a salt-containing seasoning, followed by fermentation with the addition of the lactic acid bacteria of the present invention. The pre-pickling and fermentation processes can be appropriately selected depending on the desired pickled product. Fermentation involves adding optional additives to the desired vegetables and fermenting them. Examples of such additives include bran, wheat bran, kelp, chili peppers, and dried tangerine peel. In addition to the above vegetables, food ingredients include raw milk, processed milk, soybeans, rice, and bran.

[0021] In the present invention, the lactic acid bacteria culture is, for example, a culture solution obtained by culturing lactic acid bacteria in a medium. The culture may contain lactic acid bacteria and / or killed cells thereof. The culture is obtained by culturing lactic acid bacteria using a known method. Media commonly used for culturing lactic acid bacteria, such as MRS medium or BCP medium, are used, and an appropriate pH, for example, 3 to 8, preferably 4 to 7, can be selected depending on the lactic acid bacteria strain. A solid medium or a liquid medium may be used for strain isolation and preservation. The culture may be performed at 15 to 45°C, preferably 18 to 40°C, and even more preferably 20 to 37°C, under anaerobic or aerobic conditions (Figure 1). The lactic acid bacteria can be collected by centrifugation of the culture.

[0022] Another aspect of the invention relates to a starter culture containing lactic acid bacteria of the KY5-ES5 strain (accession 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 bacterial flora. The starter culture may be a freeze-dried powder of an isolated culture of lactic acid bacteria or cells collected from the culture, or a culture containing lactic acid bacteria or a frozen product thereof. Examples of starter cultures include dried cells and rice bran beds. A culture in the logarithmic growth phase obtained by pre-cultivating the culture before adding it to a food ingredient may also be used as the starter culture.

[0023] One aspect of the present invention relates to a method for producing a fermented food, comprising the step of inoculating a food 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 as part of a separately produced fermented product. After contacting the lactic acid bacteria or a culture thereof with the food material, a fermentation step is carried out. Here, "contact" includes adding the lactic acid bacteria or a culture thereof to the food material and adding the food material to the lactic acid bacteria or a culture thereof, and further mixing may be carried out. The fermentation step may be carried out under appropriate temperature control or at ambient temperature. From the viewpoint of exhibiting spinnability, the culture is preferably carried out at 30°C or below, more preferably at 25°C or below, and even more preferably at 20°C or below. The lower limit of the temperature may be selected as the temperature at which fermentation occurs, and is usually 12°C or above, preferably 15°C or above. The fermentation period is selected appropriately depending on the type of food to achieve a good taste.

[0024] More specifically, a method for producing fermented soymilk with spinnability includes the steps of inoculating fermented soymilk with lactic acid bacteria, Lactiplantibacillus plantarum, accession number NITE P-04000, and culturing the soymilk at 15 to 30°C, more preferably 25°C or lower, and even more preferably 20°C or lower. When producing fermented soymilk, the lower the culture temperature, the higher the spinnability that can be imparted (FIG. 1). The fermentation temperature can also be selected to be 20°C, 18°C, or 16°C.

[0025] Yet another specific example is a method for producing spinnable fermented milk, which includes the steps of inoculating milk with lactic acid bacteria, Lactiplantibacillus plantarum, having accession number NITE P-04000, and culturing the milk 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, i.e., yogurt, has high spinnability even when cultured at 30° C.

[0026] A mutant strain refers to a strain in which an artificial or accidental mutation has been introduced into an isolated strain. Mutant strains can arise naturally by subculturing an isolated strain, or by chemical treatment using mutagens, such as chemicals that cause mutations, or physical treatment using ultraviolet light, X-rays, gamma rays, etc. Chemical treatments can include substances that act on nucleic acids to cause mutations, such as nitrous acid, hydroxylamine, and acridine, as well as base analogs, such as 5-bromouracil and 2-aminopurine.

[0027] All documents mentioned herein are incorporated by reference in their entirety.

[0028] The following examples of the present invention 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 claims. The present invention may be modified, for example, by adding, deleting, or substituting components of the present invention, provided that the modifications do not depart from the spirit of the present invention.

[0029] Example 1: Screening Twenty fermented pickles were collected from across Japan. Specifically, three smoked pickled radishes from Akita, three pickled nozawana from Nagano, three pickled takuan from Aichi, one pickled pesora from Yamagata, one pickled cucumber in rice bran from Nara, four pickled shiba from Kyoto, three pickled Hiroshimana from Hiroshima, and two pickled takana from Fukuoka. The fermented pickles were washed and the resulting wash solution was smeared onto MRS (Becton Dickinson) plates and anaerobically cultured at 30°C or 37°C for at least 24 hours. Colonies were picked with a sterilized toothpick, with 10-20 colonies per plate as a guideline, and evaluated visually for spinnability. Fifty-six colonies that showed spinnability were selected and inoculated onto new MRS plates. The strains were then cultured again at the same culture temperature (30°C or 37°C) under anaerobically for 24 hours, and the fungal cells were collected with a platinum loop and evaluated for spinnability again. One colony that showed the strongest spinnability was selected and designated KY5-ES5.

[0030] A glycerol stock of the isolated bacteria was smeared onto an MRS plate and cultured anaerobically at 37°C overnight using an Anaeropack. One loopful of the resulting bacteria was inoculated into 7 mL of MRS liquid medium placed in a 7 mL screw-cap test tube and cultured statically at 37°C for 24 hours. One mL of the resulting culture was centrifuged at 6000 xg, 20°C, and 5 minutes to recover the bacteria. The resulting bacteria were resuspended in sterile water, and DNA was extracted using Quick-DNA Fungal / Bacterial Kit Miniprep (Zymoresearch). Using the resulting DNA as a template, a DNA fragment was obtained by PCR using the following primers that amplify the 16S rRNA gene and recA gene region. The resulting DNA fragments were sequenced. Portions of the resulting sequences with a quality score of 40 or higher were excised and used for subsequent analysis. From the sequence information, sequence analysis of the 16S rRNA and recA genes was performed, and the species of the bacterium was identified as Lactiplantibacillus plantarum. The KY5-ES5 strain was deposited at the National Institute of Technology and Evaluation (NPMD) Patent Microorganisms Depositary (2-5-8 Kazusa Kamatari, Kisarazu City, Chiba Prefecture) (Accession Number: NITE P-04000, Date of Deposit: October 25, 2023). Furthermore, for phylogenetic analysis, the recA gene sequences of the strains listed in Figure 7 were downloaded from GenBank, a database provided by the National Center for Biotechnology Information. The recA gene sequences of all strains to be analyzed were aligned using MAFFT. The aligned base sequences were converted to PHYLIP format, and a phylogenetic tree was estimated using RAxML. The estimated results were visualized using FigTree to obtain a phylogenetic tree (Figure 7).

[0031] Since the KY5-ES5 strain is Lactiplantibacillus plantarum, glycerol stocks of 38 strains, including 35 in-house Lactiplantibacillus plantarum strains and two publicly available strains (JCM1100 and JCM1149T: RIKEN), were smeared onto MRS plates and cultured anaerobically at 37 ° C overnight using an Anaeropack. One platinum loop of the resulting 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. The turbidity (OD) of the resulting culture was measured at a wavelength of 600 nm, and the culture was inoculated into 40 mL of unadjusted soy milk (Kikkoman Corporation) in a 50 mL centrifuge tube so that the OD was 0.1. The culture was allowed to stand for 24 hours at 30°C or 20°C. After fermentation, the solid matter obtained was homogenized by stirring the entire centrifuge tube 10 times with a spoon, and then the solid matter was scooped up and spilled with a spoon, and the spinnability of the fermented soy milk was qualitatively evaluated visually. The results are shown below: As a result, more than half of the strains did not form a curd at 20°C, and even for strains that formed a curd, the curd remained lumpy and did not exhibit spinnability. On the other hand, the KY5-ES5 strain formed a smooth solid and exhibited spinnability. At 30°C, all strains formed a curd, but many lumps remained even after stirring, and did not exhibit spinnability.

[0032] Example 2: Growth Evaluation of KY5-ES5 Strain A glycerol stock of the isolated KY5-ES5 strain was smeared onto an MRS plate and cultured anaerobically at 37°C overnight using an Anaeropack. One loopful of the resulting cells was inoculated into 7 mL of MRS liquid medium placed in a 7 mL screw-cap test tube and cultured statically at 37°C for 24 hours. Cells were recovered from the culture by centrifugation at 6000 xg and 20°C for 5 minutes. The cells were washed twice with sterile saline. The OD of the resulting cell suspension was measured (wavelength 600 nm), and 15 mL of MRS liquid medium placed in a 15 mL screw-cap test tube was inoculated to an OD600 of 0.01. Static culture was performed at the following temperatures: 42°C, 37°C, 30°C, 25°C, and 20°C. The results are shown in Figure 1.

[0033] Example 3: Quantitative comparison of spinnability of fermented soy milk using KY5-ES5 strain. Glycerol stocks of Lactiplantibacillus plantarum strains JCM1100, JCM1149T, and KY5-ES5 were smeared onto MRS plates and cultured anaerobically overnight at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains) using an Anaeropack. One loopful of the resulting cells was inoculated into 7 mL of MRS liquid medium placed in a 7 mL screw-cap test tube and cultured statically for 24 hours at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains). The OD (wavelength 600 nm) of the resulting culture was measured, and the culture was inoculated into 200 mL of unadjusted soy milk (Kikkoman Corporation) in a 200 mL beaker to an OD of 0.1. The culture was anaerobically cultured for 16 or 24 hours using an Anaeropack at 37°C, 30°C, 25°C, or 20°C. After fermentation, the culture was stored at 4°C for at least 3 hours to stabilize the temperature. While maintaining the temperature on ice, the entire container was stirred 10 times with a spoon to ensure uniformity. A sample was placed in a Zahn Cup 417 No. 7 (Rigo Co., Ltd.), and the time (seconds) from when the sample separated from the hole in the bottom to when the fermented soy milk stopped flowing was measured. However, if the sample had extremely low fluidity and flow did not begin immediately after separation, the result was recorded as "not discharged." The results are shown in Figure 2. The fermented product of the KY5-ES5 strain showed no spinnability when fermented at 37°C, but the spinnability increased the lower the temperature at which it was cultured.

[0034] Example 4: Quantitative Comparison of Spinnability of Fermented Milks Glycerol stocks of Lactiplantibacillus plantarum strains JCM1100, JCM1149T, and KY5-ES5 were smeared onto MRS plates and cultured anaerobically overnight at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains) using an Anaeropack. One loopful of the resulting cells was inoculated into 7 mL of MRS liquid medium placed in a 7 mL screw-cap test tube and cultured statically for 24 hours at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains). The OD (wavelength 600 nm) of the resulting culture was measured, and 200 mL of unadjusted milk (Meiji Co., Ltd.) placed in a 200 mL beaker was inoculated with the culture to an OD of 0.6. The culture was anaerobically cultured for 24 hours using an Anaeropack at 30°C or 20°C. After fermentation, the culture was stored at 4°C for at least 3 hours to stabilize the temperature. While maintaining the temperature on ice, the entire container was stirred 10 times with a spoon to homogenize. A sample was placed in a Zahn Cup 417 No. 7 (Rigo Co., Ltd.), and the time (in seconds) from when the fermented milk flowed out through a hole in the bottom to when it stopped flowing was measured. The results are shown in Figure 3. Fermented milk fermented with the KY5-ES5 strain exhibited high spinnability, even when fermented at 30°C.

[0035] Example 5: Quantitative Comparison of Spinnility in MRS Medium Glycerol stocks of Lactiplantibacillus plantarum strains JCM1100, JCM1149T, and KY5-ES5 were smeared onto MRS plates and cultured anaerobically overnight at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains) using an Anaeropack. One loopful of the resulting cells was inoculated into 7 mL of MRS liquid medium placed in a 7 mL screw-cap test tube and cultured statically for 24 hours at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains). Cells were harvested from the resulting culture by centrifugation at 6000 x g and 20°C for 5 minutes. The resulting bacterial solution was washed twice with sterile saline. The OD of the resulting bacterial solution was measured (wavelength 600 nm), and the culture solution was inoculated into 100 mL of MRS liquid medium placed in a 100 mL medium bottle so that the OD was 0.01. Static culture was performed at 37°C, 30°C, or 25°C for 24 hours, or at 20°C for 48 hours. After culture was completed, the sample was placed in a water bath set at 25°C for 10 minutes or more to stabilize the temperature. A sample was placed in a Zahn Cup 417 No. 7 (manufactured by Rigo Co., Ltd.), and the time (in seconds) from when the medium flowed out through the hole in the bottom until it stopped flowing was measured. The results are shown in Figure 4. MRS medium containing proteins fermented with the KY5-ES5 strain exhibited low spinnability when fermented at 37°C, and spinnability increased as the temperature decreased.

[0036] Example 6: Quantitative Comparison of Spinnility in Protein-Free Synthetic Medium Glycerol stocks of Lactiplantibacillus plantarum strains JCM1100, JCM1149T, and KY5-ES5 were smeared onto MRS plates and cultured anaerobically overnight at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains) using an Anaeropack. One loopful of the resulting cells was inoculated into 7 mL of MRS liquid medium in a 7 mL screw-cap test tube and cultured statically for 24 hours at 30°C (JCM1149T strain) or 37°C (JCM1100 and KY5-ES5 strains). The resulting culture medium was centrifuged at 6000 x g and 20°C for 5 minutes to recover bacterial cells. The cells were washed twice with sterile saline. LABMM80 containing Tween 80 as a surfactant was used as the synthetic medium (Table 3). The OD of the resulting bacterial solution was measured (wavelength 600 nm), and the culture was inoculated into 100 mL of synthetic medium placed in a 100 mL medium bottle to achieve an OD of 0.1. Static culture was performed at 30°C for 24 hours. After completion of the culture, the bottle was placed in a water bath set at 25°C for at least 10 minutes to stabilize the temperature. A sample was placed in a Zahn Cup 417 No. 2 (Rigo Co., Ltd.), and the time (in seconds) from when the medium flowed out through the hole in the bottom to when it ceased to flow was measured. The results are shown in Figure 5. Protein-free LABMM80 medium fermented with the KY5-ES5 strain exhibited poor spinnability, and the Zahn Cup 417 No. 2, spinnability could be measured, and spinnability was increased by using this strain.

[0037] Example 7: Thermal Stability of Spinnability A glycerol stock of Lactiplantibacillus plantarum KY5-ES5 strain was smeared onto an MRS plate and cultured anaerobically at 37°C overnight using an Anaeropack. One loopful of the resulting cells was inoculated into 7 mL of MRS liquid medium placed in a 7 mL screw-cap test tube and cultured statically at 37°C for 24 hours. The resulting culture was centrifuged at 6000 xg, 20°C, and 5 minutes to recover the cells. The cells were washed twice with sterile saline. The OD of the resulting cell suspension was measured (at 600 nm wavelength), and the culture was inoculated into 500 mL of MRS liquid medium placed in a 500 mL medium bottle to an OD of 0.01. The culture was then cultured statically at 20°C for 48 hours. After incubation, the culture was divided into two portions, one of which was kept at 20°C, and the other was placed in a water bath set at 25°C for 10 minutes or more to stabilize the temperature. A sample was placed in a Zahn Cup 417 No. 7 (manufactured by Rigo Co., Ltd.), and the time (in seconds) from when the medium flowed out of the hole in the bottom until it stopped was measured. This was designated the value at 0 minutes of heating. The culture measured at 0 minutes of heating was placed in a water bath set at 37°C, and the heating time was measured starting from when the culture temperature reached 37°C. After 10, 20, 30, and 40 minutes of heating, the culture was removed and placed in a 25°C water bath to stabilize the temperature. When the sample heated for 40 minutes was obtained, the culture that had been kept at 20°C was also placed in a 25°C water bath at the same time to stabilize the temperature. This sample was designated the sample held at 20°C for 40 minutes. Once the temperature stabilized, the Zahn Cup 417 No. The sample was placed in a centrifuge tube (product of Rigo Co., Ltd.) No. 7, and the time (in seconds) until the medium began to flow out of the hole at the bottom and stopped flowing was measured. The results are shown in Figure 6.

[0038] NITE P-04000

Claims

1. A lactic acid bacterium, Lactiplantibacillus plantarum, accession number: NITE P-04000.

2. A culture comprising the lactic acid bacteria of claim 1.

3. The culture according to claim 2, which has spinnability.

4. The culture of claim 3, wherein the culture is fermented soy milk or fermented milk.

5. A food product comprising the lactic acid bacteria according to claim 1 or a culture thereof.

6. A starter culture comprising the lactic acid bacterium or a culture thereof according to claim 1.

7. A method for producing a fermented food having spinnability, comprising the steps of inoculating a food raw material with lactic acid bacteria, Lactiplantibacillus plantarum, having accession number NITE P-04000; and culturing the food raw material at 15°C to 30°C.

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