Lactobacillus paracasei subsp. Paracasei GXUN74722 and application thereof

Abstract

The invention relates to the field of microorganisms, in particular to a lactobacillus paracasei subsp. Paracasei GXUN74722 strain and application thereof. The invention provides a strain of Lactobacillus paracasei subsp. Paracasei GXUN74722 and a preparation method thereof. The strain is separated from traditional sour congee in Fusui County of Chongzuo Chongzuo Chongzuo Autonomous District of Guangxi Zhuang, and has good acid production capacity, cholate tolerance and intestinal adhesion capacity. The strain is sensitive to antibiotics such as ampicillin, erythromycin and tetracycline; harmful metabolites such as tyramine, histamine, cadaverine and tryptamine are not generated in the fermentation process; therefore, the strain is relatively high in safety and can be applied to food fermentation. When the strain is inoculated to ferment sour porridge, the fermentation time of the sour porridge can be shortened, the safety of food is improved, and the strain has a good application prospect in the aspect of cereal fermented food.

Description

Technical Field

[0001] The present invention relates to the field of microorganisms, and particularly to a strain of Lacticaseibacillus paracasei subsp. paracasei GXUN74722 and its application. Background Art

[0002] Sour porridge, also known as sour rice soup or sour distiller's grains, originated in the Northern Song Dynasty (960 AD - 1279 AD) and is one of the typical non-alcoholic cereal fermented foods in Asia. In China, sour porridge is a cereal fermented food with very local characteristics in Guangxi, Shanxi, and the western part of Inner Mongolia. It has a very unique taste and certain nutritional value, and is widely loved by local people. Sour porridge is a kind of food made from grains such as broomcorn millet, rice, millet, and glutinous rice and water, and is naturally fermented by microorganisms in the environment. This production method effectively retains probiotics such as lactic acid bacteria in it, endowing it with rich nutritional components and unique flavors.

[0003] Lactic acid bacteria are almost present in all traditional fermented foods. During the fermentation process, lactic acid bacteria fermentation plays a dominant role. Fermenting starch raw materials can also increase the organic acid content of the product, thereby inhibiting the growth of bacteria and molds, and improving the shelf life and safety of the food. Therefore, the related research on lactic acid bacteria fermented foods has always been one of the hotspots in the research of fermented foods. At present, the fermentation of sour porridge products is still mainly small-scale home fermentation, with problems such as low fermentation efficiency, uneven quality of fermented products, and inability to guarantee safety. Isolating and identifying probiotics that can be applied to the fermentation of sour porridge has a great promoting effect on the development of the sour porridge industry and the economy of related regions. Summary of the Invention

[0004] The purpose of the present invention is to provide a strain of Lacticaseibacillus paracasei subsp. paracasei GXUN74722 and its application to solve the problems existing in the above-mentioned prior art. The Lacticaseibacillus paracasei subsp. paracasei GXUN74722 of the present invention can be used as an alternative strain for sour porridge fermentation, improving the success rate of sour porridge fermentation and the safety of food, and having good application prospects in cereal fermented foods.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] The present invention provides a strain of Lacticaseibacillus paracasei subsp. paracasei GXUN74722, and the preservation number of the Lacticaseibacillus paracasei subsp. paracasei GXUN74722 is CGMCC No. 33135.

[0007] The present invention provides the application of the above-mentioned Lacticaseibacillus paracasei subsp. paracasei GXUN74722 in the preparation of a sour porridge starter.

[0008] The present invention provides a fermenting agent for acid porridge, and the fermenting agent for acid porridge includes the above-mentioned Lactobacillus paracasei subsp. paracasei GXUN74722.

[0009] Preferably, the fermenting agent for acid porridge further includes auxiliary materials.

[0010] The present invention provides the application of the above-mentioned Lactobacillus paracasei subsp. paracasei GXUN74722 or the above-mentioned fermenting agent for acid porridge in the preparation of acid porridge.

[0011] The present invention provides a method for preparing acid porridge, including the steps of inoculating the above-mentioned fermenting agent for acid porridge into the material to be fermented and performing fermentation to obtain the acid porridge.

[0012] Preferably, during inoculation, the inoculation amount of the fermenting agent for acid porridge is 12.5% of the volume of the material to be fermented.

[0013] More preferably, Lactobacillus paracasei subsp. paracasei GXUN74722 in the fermenting agent for acid porridge exists in the form of a fermentation broth or a bacterial suspension.

[0014] Preferably, the fermentation time is 120 h and the temperature is 37 °C.

[0015] Preferably, the material to be fermented includes grains.

[0016] More preferably, the grains include one or more of broomcorn millet, rice, millet, and glutinous rice.

[0017] The present invention provides the application of the above-mentioned Lactobacillus paracasei subsp. paracasei GXUN74722 or the above-mentioned fermenting agent for acid porridge in one or more of the following,

[0018] 1) increasing the total protein content of acid porridge;

[0019] 2) increasing the total amino acid content of acid porridge;

[0020] 3) increasing the lactic acid content of acid porridge;

[0021] 4) increasing the acidity of acid porridge;

[0022] 5) decreasing the pH of acid porridge.

[0023] The present invention discloses the following technical effects:

[0024] The present invention provides a strain of Lacticaseibacillus paracasei subsp. paracasei GXUN74722, which is isolated from traditional fermented sour porridge in Fusui County, Chongzuo City, Guangxi Zhuang Autonomous Region. It has good acid-producing ability and can be used for sour porridge fermentation. After inoculating this strain and continuously fermenting for 120 h, the obtained sour porridge has a pH of 3.22, an acidity value of 4.03 °T, a total protein content of 5240 μg / mL, a total amino acid content of 2425.93 μmoL / mL, and a lactic acid content of 19.86 mmol / L. Nutrient-rich sour porridge products can be obtained in a relatively short time, and it is superior to the index level of naturally fermented sour porridge. This strain is derived from fermented foods. As a probiotic, it has good acid-producing ability, bile salt tolerance, and adhesion ability, which can ensure its function in the intestine. Applied to the sour porridge fermentation industry, it can play important biological functions such as improving food quality and nutrition, promoting digestion and absorption, and enhancing immunity. As an alternative strain for sour porridge fermentation, it can improve the safety of sour porridge fermented foods and has good application prospects in cereal fermented foods. Brief Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is the 16S rDNA phylogenetic tree of strain GXUN74722;

[0027] Figure 2 It is the Gram staining microscopic examination image of strain GXUN74722; among them, the scale is 1000×;

[0028] Figure 3 It is the growth curve of Lacticaseibacillus paracasei subsp. paracasei GXUN74722;

[0029] Figure 4 It is the acid production effect diagram of Lacticaseibacillus paracasei subsp. paracasei GXUN74722;

[0030] Figure 5 It is the bile salt tolerance detection diagram of Lacticaseibacillus paracasei subsp. paracasei GXUN74722;

[0031] Figure 6Detection chart of the amino acid decarboxylase activity of Lactobacillus paracasei subsp. paracasei GXUN74722; among them, A is the blank group; B-E are the detection charts of the amino acid decarboxylase activities of tyrosine, histidine, lysine, and tryptophan in Lactobacillus paracasei subsp. paracasei GXUN74722 in sequence; F is the positive control, the detection chart of the amino acid decarboxylase activities of tyrosine, histidine, lysine, and tryptophan in Salmonella ATCC 14028.

[0032] Figure 7 Hemolytic detection chart of Lactobacillus paracasei subsp. paracasei GXUN74722; among them, A is the positive control, Staphylococcus aureus (S. aureus) ATCC 25923; B is Lactobacillus paracasei subsp. paracasei GXUN74722.

[0033] Figure 8 pH change chart of acid porridge during the continuous fermentation of Lactobacillus paracasei subsp. paracasei GXUN74722 for 120 h.

[0034] Figure 9 Titratable acid change chart of acid porridge during the continuous fermentation of Lactobacillus paracasei subsp. paracasei GXUN74722 for 120 h.

[0035] Figure 10 Total protein content change chart of acid porridge during the continuous fermentation of Lactobacillus paracasei subsp. paracasei GXUN74722 for 120 h.

[0036] Figure 11 Total amino acid content change chart of acid porridge during the continuous fermentation of Lactobacillus paracasei subsp. paracasei GXUN74722 for 120 h.

[0037] Figure 12 Lactic acid content change chart of acid porridge during the continuous fermentation of Lactobacillus paracasei subsp. paracasei GXUN74722 for 120 h. Detailed implementation manners

[0038] The various exemplary implementation manners of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0039] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0041] Without departing from the scope or spirit of the present invention, various modifications and variations can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0042] Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0043] The present invention provides a strain of Lacticaseibacillus paracasei subsp. paracasei isolated from traditional fermented sour porridge in Guangxi, with the strain name of Lacticaseibacillus paracasei subsp. paracasei GXUN74722, classified and named as Lacticaseibacillus paracasei subsp. paracasei, deposited in the General Microbiological Center of the China General Microbiological Culture Collection Center (CGMCC), with the deposit number of CGMCC No. 33135. Lacticaseibacillus paracasei subsp. paracasei GXUN74722 isolated from traditional fermented food sour porridge in Guangxi is easy to culture, grows relatively fast, has strong acid-producing ability, bile salt tolerance, and high safety, and can be used as a sour porridge fermentation bacterium in the sour porridge fermentation industry. Using the isolated Lacticaseibacillus paracasei subsp. paracasei GXUN74722 of the present invention as a single strain for sour porridge fermentation can make the indicators such as the pH, titratable acidity, total protein content, and total amino acid content of the sour porridge better than those of naturally fermented sour porridge. It is preliminarily determined that this strain can be used as an alternative strain for sour porridge fermentation.

[0044] The following is a detailed description of the embodiments of the present invention.

[0045] Example 1

[0046] In this example, a strain was isolated and screened from traditional fermented sour porridge in Fusui County, Chongzuo City, Guangxi Zhuang Autonomous Region, and named GXUN74722. Its 16S rDNA sequence was sequenced and a phylogenetic tree was constructed, and the results are as Figure 1 shown. The results show that strain GXUN74722 is in the same branch as Lactobacillus paracasei subsp. paracasei.

[0047] The 16S rDNA sequence of strain GXUN74722 is as follows:

[0048] GATGTGGGTCTATACATGCAAGTCGAACGAGTTCTCGTTGATGATCGGTGCTTGCAC

[0049] CGAGATTCAACATGGAACGAGTGGCGGACGGGTGAGTAACACGTGGGTAACCTGCCCT

[0050] TAAGTGGGGGATAACATTTGGAAACAGATGCTAATACCGCATAGATCCAAGAACCGCAT

[0051] GGTTCTTGGCTGAAAGATGGCGTAAGCTATCGCTTTTGGATGGACCCGCGGCGTATTAGC

[0052] TAGTTGGTGAGGTAACGGCTCACCAAGGCGATGATACGTAGCCGAACTGAGAGGTTGAT

[0053] CGGCCACATTGGGACTGAGACACGGCCCAAACTCCTACGGGAGGCAGCAGTAGGGAAT

[0054] CTTCCACAATGGACGCAAGTCTGATGGAGCAACGCCGCGTGAGTGAAGAAGGCTTTCG

[0055] GGTCGTAAAACTCTGTTGTTGGAGAAGAATGGTCGGCAGAGTAACTGTTGTCGGCGTGA

[0056] CGGTATCCAACCAGAAAGCCACGGCTAACTACGTGCCAGCAGCCGCGGTAATACGTAGG

[0057] TGGCAAGCGTTATCCGGATTTATTGGGCGTAAAGCGAGCGCAGGCGGTTTTTTAAGTCTG

[0058] ATGTGAAAGCCCTCGGCTTAACCGAGGAAGCGCATCGGAAACTGGGAAACTTGAGTGC

[0059] AGAAGAGGACAGTGGAACTCCATGTGTAGCGGTGAAATGCGTAGATATATGGAAGAACA

[0060] CCAGTGGCGAAGGCGGCTGTCTGGTCTGTAACTGACGCTGAGGCTCGAAAGCATGGGT

[0061] AGCGAACAGGATTAGATACCCTGGTAGTCCATGCCGTAAACGATGAATGCTAGGTGTTG

[0062] GAGGGTTTCCGCCCTTCAGTGCCGCAGCTAACGCATTAAGCATTCCGCCTGGGGAGTAC

[0063] GACCGCAAGGTTGAAACTCAAAGGAATTGACGGGGGCCCGCACAAGCGGTGGAGCAT

[0064] GTGGTTTAATTCGAAGCAACGCGAAGAACCTTACCAGGTCTTGACATCTTTTGATCACCT

[0065] GAGAGATCAGTTTCCCCTTCGGGGCAAATGACAGGTGGTGCATGATGTCGTCAGCTCGT

[0066] GTCGTGAGATGTGGTAGTCCCGCACGAGCGCACCCGTATGACTAGTGCAGCATTTAGTG

[0067] GCACTCTAGTAGACTGCGTGAACAACGGAGAGTGGGCATGACGTCCAATCATCATGCCG

[0068] TTAGACCTGCTACCACTGCCTACATTGATGTGGTCACAACAGAGATTGCGCAGAGACTG

[0069] CTC (SEQ.ID NO.1).

[0070] Meanwhile, morphological, physiological and biochemical identifications were carried out with reference to the "Manual for the Identification of Common Bacteria". Through Gram staining and microscopic examination, it was found that strain GXUN74722 was a Gram-positive bacterium ( Figure 2 ). The results of physiological and biochemical identification are shown in Table 1, and the results show that strain GXUN74722 can produce acid, can synthesize and secrete protease and tryptophanase, and does not have the ability to synthesize cellulase, catalase, amylase, urease and nitroreductase.

[0071] Table 1 Physiological and Biochemical Identification Table

[0072] Experiment category Result Acid production + Cellulase - Catalase - Amylolytic enzyme - Proteolytic enzyme + Urease - Tryptophanase + Nitroreductase -

[0073] Note: "+" indicates positive and "-" indicates negative.

[0074] In summary, through molecular biology, morphological analysis and physiological and biochemical detection, strain GXUN74722 was identified as Lactobacillus paracasei subsp. paracasei, and its taxonomic name was determined as Lactobacillus paracasei subsp. paracasei. The strain GXUN74722 of the present invention was named Lactobacillus paracasei subsp. paracasei GXUN74722, and was deposited in the China General Microbiological Culture Collection Center (CGMCC) on December 20, 2024. The deposit address is the Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing, and the deposit number is CGMCC No. 33135.

[0075] Example 2

[0076] In this example, the growth curve, acid production performance (acid production ability on CaCO 3 -MRS solid medium), bile salt tolerance and intestinal adhesion ability, drug sensitivity and safety of Lactobacillus paracasei subsp. paracasei GXUN74722 were evaluated, and the results are as follows:

[0077] The growth curve of Lactobacillus paracasei subsp. paracasei GXUN74722 was plotted, and the results are as Figure 3 shown. The results show that the strain grew well, had a relatively long logarithmic phase, reached the stationary phase at 12 h, and the OD 600 in the stationary phase reached 1.50, and the pH of the fermentation broth decreased with the extension of fermentation time.

[0078] Detect the size of the transparent zone of Lactobacillus paracasei subsp. paracasei GXUN74722 on CaCO 3 -MRS solid medium, and the results are as Figure 4 shown. The results show that the strain has good acid-producing performance, and the diameter of the transparent zone produced by culturing on CaCO 3 -MRS solid medium is 11 mm.

[0079] Detect the OD of Lactobacillus paracasei subsp. paracasei GXUN74722 in MRS liquid medium containing different concentrations of bile salts 600 , and the results are as Figure 5 shown. The results show that the strain has good bile salt tolerance, and the OD 600 reaches 0.10 when the bile salt concentration is 0.3%.

[0080] Detect the hydrophobicity and self-coagulation of Lactobacillus paracasei subsp. paracasei GXUN74722, and the results are shown in Table 2. The results show that the strain has good intestinal adhesion ability, and the hydrophobicity and self-coagulation reach more than 80%.

[0081] Table 2 Detection of hydrophobicity and self-coagulation

[0082]

[0083] Note: The table data are for 3 replicates, and ± represents the standard deviation.

[0084] Detect the diameter of the inhibition zone of Lactobacillus paracasei subsp. paracasei GXUN74722 under different antibiotics, and the results are shown in Table 3. The results show that the strain is sensitive to ampicillin, erythromycin and tetracycline.

[0085] Table 3 Antibiotic sensitivity detection

[0086]

[0087] Note: Sensitive (S), Intermediate (I), Resistant (R) in the table

[0088] Amino acid decarboxylase can decarboxylate amino acids to produce biogenic amines, and biogenic amines are a class of active, nitrogen-containing, low-molecular-weight organic compounds with strong toxicity. Human intake is not conducive to health and can endanger life in severe cases. If a strain can encode and synthesize amino acid decarboxylase, it will decarboxylate amino acids to form biogenic amines. Detect the amino acid decarboxylase activity of Lactobacillus paracasei subsp. paracasei GXUN74722. Inoculate Lactobacillus paracasei subsp. paracasei GXUN74722 and Salmonella ATCC 14028 into the medium containing 4 amino acids, namely tyrosine, histidine, lysine, and tryptophan, and observe the color change of the medium. The results are as Figure 6As shown, the medium inoculated with the positive control strain Salmonella ATCC 14028 showed a purple color, indicating positive amino acid decarboxylase activity; the blank medium served as a blank control, showing a yellow color, which was a negative result. The media inoculated with the strain Lactobacillus paracasei subsp. paracasei GXUN74722 all showed a yellow color, indicating negative amino acid decarboxylase activity. This shows that this strain does not produce harmful metabolites such as tyramine, histamine, cadaverine, and tryptamine.

[0089] The hemolytic phenomenon of Lactobacillus paracasei subsp. paracasei GXUN74722 was detected, with Staphylococcus aureus (S. aureus) ATCC 25923 as the control. The results are as Figure 7 shown. The results showed that Lactobacillus paracasei subsp. paracasei GXUN74722 had no hemolytic zone, and its hemolytic property was negative.

[0090] In summary, through the analysis of the growth curve, acid production performance, bile salt tolerance, and safety of the strain Lactobacillus paracasei subsp. paracasei GXUN74722, it was proved that this strain had good activity, and the diameter of the transparent zone on the CaCO 3 -MRS solid medium reached 11 mm. At the same time, this strain had a good growth state, strong acid production, bile salt tolerance, and adhesion ability, was non-toxic and harmless, had excellent performance and was safe, and could be used for the fermentation of sour porridge.

[0091] Example 3

[0092] This example provides a method for preparing sour porridge. This method uses Lactobacillus paracasei subsp. paracasei GXUN74722 screened in Example 1 for fermentation to obtain sour porridge, which specifically includes the following steps:

[0093] Step 1. Cultivate Lactobacillus paracasei subsp. paracasei GXUN74722 to obtain a fermentation broth; the cultivation method is: inoculate Lactobacillus paracasei subsp. paracasei GXUN74722 on MRS solid medium, cultivate at 37 °C for 48 h to obtain single colonies, pick a single colony and inoculate it into MRS broth medium, and cultivate at 37 °C and 200 r / min with shaking for 24 h to obtain a fermentation broth with an OD 600 of 1.0.

[0094] Step 2. After washing the rice, load water and rice into a fermentation bottle according to a volume ratio of 5:1 and perform high-pressure steam sterilization (105 °C, 5 min) to obtain a rice medium.

[0095] Step 3. Inoculate and ferment the fermentation broth with an inoculum size of 12.5% (V / V). Before inoculation, the fermentation broth is centrifuged and resuspended twice to obtain a bacterial suspension. Specifically: First, centrifuge the fermentation broth at 3500 r / min for 10 min, discard the supernatant, add physiological saline to the bacterial precipitate to resuspend it to the original volume, then centrifuge again, and add an equal volume of 2% glucose solution to the precipitate to resuspend it to obtain a bacterial suspension.

[0096] Step 4. After inoculating the bacterial suspension into the rice medium and stirring evenly, place it in an incubator and ferment continuously at 37 °C for 120 h to obtain sour porridge, denoted as GXUN74722.

[0097] Comparative Example 1

[0098] Natural fermentation of rice to obtain naturally fermented sour porridge. Specifically: After washing the rice, load water and rice into a fermentation bottle according to a volume ratio of 5:1 to prepare a rice medium. Add a 2% glucose solution with the same volume as the bacterial suspension in Example 3 to the rice medium, stir evenly, then place it in an incubator and ferment continuously at 37 °C for 120 h to obtain naturally fermented sour porridge, denoted as ZR.

[0099] Effect Example

[0100] 1. Detection of pH and titratable acid during fermentation

[0101] The pH and titratable acid of the sour porridge samples obtained from Example 3 and Comparative Example 1 after continuous fermentation for 120 h were detected, and the results are as Figure 8 、 Figure 9 shown.

[0102] As Figure 8 shown, after 120 h of fermentation in Example 3 and Comparative Example 1, the pH of both decreased, but the pH of the inoculated sour porridge sample decreased faster than that of natural fermentation, reaching 3.22.

[0103] As Figure 9 shown, after 120 h of fermentation in Example 3 and Comparative Example 1, the titratable acidity value of Example 3 showed an upward trend, and the acidity value of the inoculated sour porridge sample was higher than that of the naturally fermented sour porridge sample, reaching 4.03 °T.

[0104] Through the analysis of the changes in pH and titratable acid during fermentation, compared with natural fermentation, after 120 h of fermentation with the artificially inoculated Lactobacillus paracasei subsp. paracasei GXUN74722, the pH of the sour porridge decreased faster and its acidity value increased faster. After fermentation was completed, it stabilized at pH 3.22 and acidity value 4.03 °T, which was better than the naturally fermented sour porridge.

[0105] 2. Detection of total protein, total amino acids, and lactic acid content during fermentation

[0106] The total protein, total amino acid, and lactic acid contents of the sour porridge samples from Example 3 and Comparative Example 1 during continuous fermentation for 120 h were detected, and the results are as Figure 10 , Figure 11 and Figure 12 shown.

[0107] As Figure 10 shown, after 120 h of fermentation in Example 3 and Comparative Example 1, the total protein contents of both changed to varying degrees. Among them, the total protein content of the inoculated sour porridge sample showed a slow increasing trend and was higher than that of the naturally fermented sour porridge sample during the fermentation process. After fermentation was completed, its content stabilized at 5240 μg / mL.

[0108] As Figure 11 shown, after 120 h of fermentation in Example 3 and Comparative Example 1, the total amino acid contents of both changed to varying degrees. Among them, the total amino acid content of the inoculated sour porridge sample was higher than that of the naturally fermented sour porridge sample during the fermentation process. After fermentation was completed, its content stabilized at 2425.93 μmoL / mL.

[0109] As Figure 12 shown, after 120 h of fermentation in Example 3 and Comparative Example 1, the lactic acid contents of both changed to varying degrees. Among them, the lactic acid content of the inoculated sour porridge sample showed a gradually increasing trend and was higher than that of the naturally fermented sour porridge sample during the fermentation process. After fermentation was completed, its content stabilized at 19.86 mmoL / L.

[0110] Through the analysis of the total protein, total amino acid, and lactic acid contents during the fermentation process, compared with natural fermentation, after 120 h of fermentation with the artificially inoculated Lactobacillus paracasei subsp. paracasei GXUN74722, the total protein content of the sour porridge was 5240 μg / mL, the total amino acid content was 2425.93 μmoL / mL, and the lactic acid content was 19.86 mmoL / L, all of which were better than those of the naturally fermented sour porridge, and the nutrition was more abundant.

[0111] In summary, a strain of Lactobacillus paracasei subsp. paracasei GXUN74722 provided by the present invention was isolated from traditional fermented sour porridge in Guangxi. It has good activity and can grow well, has good acid-producing ability and bile salt tolerance, and can be used for fermenting sour porridge. After inoculating Lactobacillus paracasei subsp. paracasei GXUN74722 and fermenting for 120 h, the pH of the sour porridge food was 3.22, the acidity value was 4.03 °T, the total protein content was 5240 μg / mL, the total amino acid content was 2425.93 μmoL / mL, and the lactic acid content was 19.86 mmoL / L. It can reach or even exceed the index level of naturally fermented sour porridge in a relatively short time, and improves the safety of the sour porridge product.

[0112] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A strain of Lactobacillus paracasei subsp. paracasei GXUN74722, characterized in that: The deposit number of the Lactobacillus paracasei subspecies paracasei GXUN74722 is CGMCC No.33135.

2. application of Lactobacillus paracasei subspecies paracasei GXUN74722 described in claim 1 in preparing sour porridge starter.

3. A sour porridge starter, characterized in that The sour porridge starter comprises the Lactobacillus paracasei subspecies paracasei GXUN74722 according to claim 1.

4. The sour porridge starter according to claim 3, characterized in that The sour porridge starter also includes auxiliary materials.

5. Application of the Lactobacillus paracasei subspecies paracasei GXUN74722 described in claim 1 or the sour porridge starter described in claim 3 or 4 in preparing sour porridge.

6. A method for preparing sour porridge, characterized in that: The method comprises the steps of inoculating the sour porridge starter described in claim 3 or 4 into the material to be fermented, and fermenting the material to obtain the sour porridge.

7. The preparation method according to claim 6, characterized in that: During the inoculation, the inoculation amount of the sour porridge starter is 12.5% ​​of the volume of the material to be fermented.

8. The preparation method according to claim 6, characterized in that: The fermentation time is 120 hours and the temperature is 37°C.

9. The preparation method according to claim 6, characterized in that: The materials to be fermented include grains.

10. Use of the Lactobacillus paracasei subspecies paracasei GXUN74722 of claim 1 or the sour porridge starter of claim 3 or 4 in any one or more of the following: 1) Increase the total protein content of sour porridge; 2) Increase the total amino acid content of sour porridge; 3) Increase the lactic acid content of sour porridge; 4) Increase the acidity of sour porridge; 5) Reduce the pH of sour porridge.

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