A high-sugar osmotic tolerance brewer's yeast strain and its application

Abstract

The present invention provides a high-sugar osmotic resistant Saccharomyces cerevisiae strain and application. The Saccharomyces cerevisiae strain provided by the present invention is: Saccharomyces cerevisiae AMCC 31195 strain (Saccharomyces cerevisiae AMCC 31195), which is deposited in the China Center for Type Culture Collection (CCTCC) with a deposit number of CCTCC NO: M 20211685. The Saccharomyces cerevisiae AMCC 31195 strain provided by the present invention has the characteristics of resistance to high sugar osmotic pressure, resistance to cold osmotic shock, and resistance to organic acids.

Description

Technical Field

[0001] The invention belongs to the field of microorganisms, and specifically relates to a yeast strain resistant to high sugar osmotic winemaking, resistant to high sugar, resistant to cold osmotic shock, and resistant to organic acid, and an application thereof. Background Art

[0002] Fermented flour products, such as steamed buns, dumplings, and bread, account for a large proportion of people's dietary structure as staple food. Yeast is an indispensable raw material in the production process of fermented flour products, and different yeasts will affect the quality and taste of fermented flour products. With the improvement of people's living standards, there are more and more demands for the quality and taste of fermented flour products, such as extended shelf life and high sugar content. Summary of the invention

[0003] In the process of making bread, a lot of sugar is often added. In a high-sugar environment, the fermentation performance of yeast drops sharply.

[0004] In the process of making bread, the ambient temperature is often too high, causing the yeast to rise too quickly during the dough mixing process, resulting in a decrease in product quality. In order to lower the temperature of the dough, low-temperature water is usually added to cool it down, but yeast cells will enter a state of shock when encountering a low-temperature environment, thus affecting the normal growth of yeast cells. Therefore, there is an urgent need for yeast to resist cold osmotic shock.

[0005] In order to extend the shelf life of bread, preservatives are usually added to bread to extend the shelf life. Commonly used preservatives in bread processing are usually organic acids and their salts, such as propionic acid, acetic acid, calcium propionate, sodium propionate and sodium acetate. These organic acids and their salts have certain side effects on the bread fermentation process and will affect the fermentation of bread dough.

[0006] It can be seen that in order to meet the actual application scenarios and preservation needs of baked products, a yeast strain that is resistant to high sugar osmotic pressure, cold osmotic shock, and organic acid is urgently needed.

[0007] The invention provides a saccharomyces cerevisiae strain. The saccharomyces cerevisiae strain is a saccharomyces cerevisiae AMCC 31195 strain (Saccharomyces cerevisiae AMCC 31195), which is deposited in China Center for Type Culture Collection (CCTCC) with a deposit number of CCTCC NO: M 20211685.

[0008] The present invention also provides a fermentation preparation method of a brewer's yeast agent, which comprises the following steps: culturing the brewer's yeast strain.

[0009] Preferably, the preparation method comprises the following steps:

[0010] (1) amplifying and culturing the Saccharomyces cerevisiae strain;

[0011] (2) Adding the product obtained in step (1) into a liquid culture medium and fermenting and culturing at 26-32°C.

[0012] The present invention also provides a bacterial agent, wherein the bacterial agent contains the Saccharomyces cerevisiae AMCC 31195 strain.

[0013] Preferably, the bacterial agent is obtained by the fermentation preparation method.

[0014] The present invention also provides application of the brewer's yeast strain or the bacterial agent in fermentation.

[0015] The invention also provides application of the brewer's yeast strain or the bacterial agent in dough.

[0016] The invention also provides a dough, wherein the dough contains the brewer's yeast strain or the bacterial agent.

[0017] Preferably, the dough contains flour and the brewer's yeast strain in a mass ratio of 100:0.5-5.

[0018] Preferably, the dough contains flour and sugar in a mass ratio of 100:0-40; preferably, the dough contains flour and sugar in a mass ratio of 100:15-40;

[0019] Preferably, the sugar is sucrose.

[0020] Preferably, the dough further contains a preservative;

[0021] Preferably, the preservative is an organic acid and its salt preservative;

[0022] Preferably, the organic acid is one or both of propionic acid and acetic acid, and the organic acid salt is one or a combination of two or more of calcium propionate, sodium propionate and sodium acetate;

[0023] Preferably, the mass ratio of flour to preservative in the dough is 100:0-1, preferably 100:0-0.6.

[0024] The present invention also provides a method for preparing the dough, which comprises the following steps: kneading the dough with water at -0-35°C.

[0025] In the present invention, the water at 0°C can be ice at 0°C, an ice-water mixture at 0°C, or liquid water at 0°C.

[0026] In the dough preparation process of the present invention, water, flour and brewer's yeast can be added in any order, such as first mixing the flour and yeast, and then adding 0-35°C water to knead the dough, or first adding flour to 0-35°C water and then adding brewer's yeast, or first adding brewer's yeast to 0-35°C water and then adding flour.

[0027] The invention also provides a flour product, which is prepared by using the dough.

[0028] Preferably, the flour product is bread.

[0029] The cerevisiae AMCC 31195 strain provided by the invention has the characteristics of resistance to high sugar osmotic pressure, resistance to cold osmotic shock and resistance to organic acid.

[0030] Strain deposit information

[0031] The Saccharomyces cerevisiae AMCC 31195 strain (Saccharomyces cerevisiae AMCC31195) provided by the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on December 29, 2021, with a deposit number of CCTCC NO: M 20211685, and a deposit address of: Wuhan University, Wuhan, China, postal code: 430072; telephone: (027)-68754052.

[0032] The Saccharomyces cerevisiae AMCC 30002 strain (Saccharomyces cerevisiae AMCC30002) provided by the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with a deposit number of CCTCC NO: M 2022338, and a deposit address: Wuhan University, Wuhan, China, postal code: 430072; telephone: (027)-68754052.

[0033] The Saccharomyces cerevisiae AMCC 30004 strain in the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with a deposit number of CCTCC NO: M2022339, and a deposit address of: Wuhan University, Wuhan, China, postal code: 430072; telephone: (027)-68754052. DETAILED DESCRIPTION

[0034] The invention uses the saccharomyces cerevisiae AMCC 30002 strain and the saccharomyces cerevisiae AMCC 30004 strain as parent strains, and hybridizes to obtain a saccharomyces cerevisiae AMCC 31195 strain which has the characteristics of high sugar osmotic pressure resistance, cold osmotic shock resistance and organic acid resistance.

[0035] First, a single spore is prepared from the parent strain using a yeast micromanipulator, and after obtaining the first-generation heterozygote, a single spore is prepared from the parent strain, and the obtained single spore is hybridized with the single spore of the parent strain of brewer's yeast AMCC 30004. After two rounds of hybridization, the obtained heterozygote is verified and the properties are screened. Then, shake flask fermentation culture is carried out to screen the biomass dry weight and fermentation activity indicators. The biomass dry weight screening standard is that the yeast milk biomass dry weight of the hybrid strain reaches 90-100%, preferably 95-100%, of any parent strain; the fermentation activity screening standard is that the fermentation activity of the yeast milk of the hybrid strain 16% sugar for 1h reaches 90-100%, preferably 95-100%, of any parent strain; the fermentation activity of 16%+1% calcium propionate for 3h reaches 85-100%, preferably 90-100%, of any parent strain.

[0036] The hybrid strain obtained by shake flask fermentation screening is cultured in a fermenter, and the yeast obtained by fermentation is used to prepare active dry yeast, and the hybrid strain without obvious abnormality in the preparation process of active dry yeast is screened, and the obtained active dry yeast is used to prepare dough containing 16% sugar + 0.6% calcium propionate, so as to screen the hybrid strain obtained by screening the active dry yeast prepared by the hybrid strain with better fermentation performance in a high sugar and organic acid environment. The screening standard is that the fermentation activity of the active dry yeast of the hybrid strain in 16% + 0.6% calcium propionate for 2 hours reaches 100-120% of any parent strain, preferably 110-120%.

[0037] Finally, the hybrid strains screened in the above steps were screened for resistance to cold osmotic shock. Crushed ice at 0°C was used to prepare 20% sugar dough containing active dry yeast of the hybrid strains, and the dough proofing time was measured. The hybrid strain with the shortest dough proofing time was selected as the target strain, thereby screening out the hybrid strain with resistance to cold osmotic shock.

[0038] The cerevisiae AMCC 31195 strain was obtained through screening, and the obtained cerevisiae AMCC 31195 strain has the performance of resistance to high sugar osmotic pressure, resistance to organic acid and resistance to cold osmotic shock.

[0039] The high-sugar yeast strain for flour with multiple industrial properties provided by the present invention can obtain baker's yeast with multiple tolerances without undergoing an acclimation process, can meet the urgent market demand for resistance to high sugar osmotic pressure, resistance to cold osmotic shock, and resistance to organic acid, and enhance the competitiveness of leading products.

[0040] The x% sugar or x% calcium propionate involved in the dough in the embodiment of the present invention means that the mass ratio of flour to sugar or flour to calcium propionate in the dough is 100:x.

[0041] The production of some sugar-free bread, soda crackers, steamed buns, etc. mainly involves fermentation of sugar-free dough. Most of the flour is starch, which is converted into maltose under the action of amylase in the flour. Therefore, the ability of yeast to utilize maltose determines the speed of rising of the sugar-free dough. The maltose utilizing enzymes of yeast include maltose hydrolase and maltose permease. Yeast with such properties is called rapid fermentation yeast.

[0042] Sugar-tolerant yeast refers to yeast that has a higher tolerance to sucrose in sugary dough, that is, its growth and fermentation performance in sugary bread is higher than that of ordinary yeast.

[0043] Low-sugar tolerant yeast is used in dough systems with about 7% sucrose, and high-sugar tolerant yeast is used in dough systems with higher sucrose concentrations, with a content of up to 25%. Sucrose cannot generally be directly utilized by microorganisms, while brewer's yeast contains sucrose hydrolase that can degrade sucrose. It acts on β-1,2 glycosidic bonds to hydrolyze sucrose into D-glucose and D-fructose. Glucose and fructose then enter the glycolysis pathway for yeast utilization. At the same time, the glucose and fructose generated by the rapid decomposition of sucrose will increase the osmotic pressure around the yeast cells. The yeast cell membrane is a selective semi-permeable biological membrane. The concentration of the outside world will affect the activity of the yeast cells. When the cells are in an environment with high osmotic pressure, the water and protoplasm in the cells will seep out of the cell membrane, causing the cells to dehydrate or even die. Therefore, the hypertonic environment faced by brewer's yeast in high-sugar dough has an impact on its growth and fermentation performance. Therefore, the gas production capacity of sugar-free yeast is determined by the activity of maltose utilization enzymes, and the gas production capacity of sugar-tolerant yeast is determined by the activity of sucrase.

[0044] The reagents and instrument information used in the examples of the present invention are shown in Table 1 below.

[0045] Table 1

[0046] Reagents / Instruments model Manufacturer Yeast extract powder Angel Yeast glucose Sinopharm Peptone Angel Yeast Agar Huixing Potassium acetate Sinopharm Shanghai Trial 2×PCR Mix Tiangen Analytical Balance ME4002E METTLER TOLEDO pH Meter PB-10 Sartorius Fast Moisture Meter MJ33 METTLER TOLEDO Clean bench SKJH-1109 Shanghai Sukun Constant temperature shaker ZWYR-2102C Shanghai Zhicheng Biochemical incubator SPX-158L Ningbo Xinzhi Constant temperature water bath HH-2 Jiangsu Guohua PCR instrument C1000 BIO-RAD Gel imaging system <![CDATA[GelDoc TM XR+]]> BIO-RAD Centrifuge DL-5200B-II Shanghai Feige Electrophoresis Apparatus EPS-300 Shanghai Tianneng UV-Visible Photometer UV2310II Hangzhou Aosheng Optical Microscope CX43 OLYMPUS Fully automatic growth curve analyzer BioscreenC OY Growth Curves Vitality Tester SJA Swedish SJA Electric blast drying oven DHG-9070A Shanghai Jinghong

[0047] The formula of the spore production medium used in the embodiment of the present invention is: 1% potassium acetate, 0.1% yeast extract powder, 0.05% glucose, and 2% agar.

[0048] In the embodiment of the present invention, each strain of Saccharomyces cerevisiae is activated using a YPD solid culture medium, wherein the formula of the YPD solid culture medium is: 1% yeast extract powder, 2% peptone, 2% glucose, and 2% agar.

[0049] In the embodiment of the present invention, each Saccharomyces cerevisiae strain is cultured in YPD liquid culture medium, and the formula of YPD liquid culture medium is: 1% yeast extract powder, 2% peptone, and 2% glucose.

[0050] Embodiment 1

[0051] The Saccharomyces cerevisiae AMCC 30002 and Saccharomyces cerevisiae AMCC 30004 were used as parent strains for hybridization.

[0052] The Saccharomyces cerevisiae AMCC30002 strain is a strain of Saccharomyces cerevisiae bred by Angel Yeast Co., Ltd. The original strain was collected from Yantai City, Shandong Province. Through optical microscopy, the colony of the Saccharomyces cerevisiae strain has a cheese-like texture, milky white color, smooth surface, neat edges, oval microscopic morphology, and budding reproduction. 26S rDNA gene identification determined that the strain is a Saccharomyces cerevisiae strain, which is a food attribute. It was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with the deposit number CCTCC NO: M 2022338.

[0053] The Saccharomyces cerevisiae AMCC30004 strain is a strain of Saccharomyces cerevisiae bred by Angel Yeast Co., Ltd. The original strain was collected from Ili Kazakh Autonomous Prefecture, Xinjiang Uygur Autonomous Region. Through optical microscopy, the colony of the Saccharomyces cerevisiae strain has a cheese-like texture, milky white color, smooth surface, neat edges, oval microscopic morphology, and budding reproduction. 26S rDNA gene identification determined that the strain is a Saccharomyces cerevisiae strain, which is a food attribute. It was deposited in the China Center for Type Culture Collection (CCTCC) on March 29, 2022, with the deposit number CCTCC NO: M 2022339.

[0054] The two parent strains produce spores under the same conditions, and the single spores are inoculated into a test tube of YPD liquid culture medium, 30℃, shake, and culture overnight. Then, according to the different matching designs, the single spores of different matching types are inoculated into the YPD liquid culture test tube in turn, 30℃, shake, and culture overnight, and then diluted and coated on the YPD plate, 30℃, shake, and culture overnight, and the growth of the colony is observed. The larger colony on the plate is selected and inoculated into a test tube of YPD liquid culture medium, 30℃, shake, and culture overnight, and the matching identification and spore test are performed on it, and the heterozygotes are selected. The obtained heterozygotes are inoculated into a 100-well culture plate filled with high-sugar culture medium, and the Bioscreen C instrument is prepared for measurement. The parameters are set: temperature 30℃, time 48h, wavelength 600nm, and data are measured every 30min, and then the growth curve is measured. According to the growth curve results, the maximum specific growth rate analysis is performed, and the specific formula is as follows:

[0055] Maximum specific growth rate (μ) = (lnOD2-lnOD1) / (t2-t1)

[0056] OD1: OD corresponding to t1 600 value;

[0057] OD2: OD corresponding to t2 600 value;

[0058] t2: end time of logarithmic growth period;

[0059] t1: starting time of logarithmic growth phase;

[0060] Based on the analysis of Bioscreen C high-throughput data results, the top three heterozygous strains with the highest specific growth rates were selected as the first-generation strong heterozygotes.

[0061] According to the above steps, single spores were prepared again, and the obtained single spores were hybridized with the cerevisiae AMCC30004 strain, and the heterozygotes were screened and verified. The above steps were repeated to obtain heterozygotes from two rounds of hybridization, and the top 100 heterozygous strains with the maximum specific growth rate in the last round of heterozygotes were selected for shake flask fermentation test.

[0062] The 100 hybrid strains obtained above were screened for hybrid strains that met the biomass index using biomass as the screening index. A shake flask experiment was performed on the hybrid strains, inoculated into a YPD liquid medium shake flask, cultured overnight at 30°C, shaken, and centrifuged to obtain yeast milk, which was then tested for moisture and its dry biomass weight was calculated. The screening standard was that the dry biomass weight of the yeast milk of the hybrid strain reached 95-100% of that of any parent.

[0063] The following tests were carried out on the hybrid strains with dry biomass advantage to screen for hybrid strains with high sugar and organic acid tolerance:

[0064] Test A: 1h fermentation activity test of 280g dough of 16% sugar dough system, the screening standard is to reach 95-100% of any parent strain;

[0065] Test B: 3h fermentation activity test of 70g dough of 16% sugar + 1% calcium propionate dough system, the screening standard is to reach 95-100% of any parent strain.

[0066] Table 2 shows the dough system formulas for Test A and Test B.

[0067] Table 2 Formula of dough system of test A and test B

[0068]

[0069]

[0070] The hybrid strains with high sugar and organic acid resistance obtained by screening were subjected to subsequent screening.

[0071] The hybrid strain with high sugar and organic acid resistance is cultured in a fermenter, and the yeast obtained by the fermenter culture is used to prepare active dry yeast, and the hybrid strain with no obvious abnormality in the dry yeast preparation process is selected. The obtained active dry yeast is used to prepare dough containing 16% sugar + 0.6% calcium propionate, so as to screen the hybrid strain obtained. The active dry yeast prepared by the hybrid strain has better fermentation performance in a high sugar and organic acid environment. The screening standard is that the fermentation activity of the active dry yeast of the hybrid strain in 16% + 0.6% calcium propionate for 2 hours reaches 100-120% of any parent strain, preferably 110-120%.

[0072] Finally, the hybrid strains obtained by the above steps, which have better fermentation performance in high sugar and organic acid environment, were screened for cold osmotic shock resistance. 20% sugar dough containing hybrid strain active dry yeast was prepared by mixing with crushed ice at 0°C, and the dough proofing time was measured. The hybrid strain with the shortest dough proofing time was selected as the target strain, thereby screening the hybrid strain with cold osmotic shock resistance.

[0073] A hybrid strain was obtained through screening that is resistant to high sugar osmotic pressure, cold osmotic shock, and organic acid. The hybrid strain was identified and the obtained yeast strain had a cheese-like colony texture, milky white color, a smooth surface, neat edges, an oval microscopic morphology, and budding reproduction.

[0074] The strain was named Saccharomyces cerevisiae AMCC 31195. The Saccharomyces cerevisiae AMCC 31195 strain was deposited in the China Center for Type Culture Collection (CCTCC) on December 29, 2021, with a deposit number of CCTCC NO.M 20211685.

[0075] Embodiment 2

[0076] Saccharomyces cerevisiae AMCC 31195 strain and parent strains Saccharomyces cerevisiae AMCC 30002 strain and Saccharomyces cerevisiae AMCC 30004 strain were inoculated into shake flasks containing YPD liquid culture medium, shaken at 30°C, and cultured overnight. Yeast milk was obtained after centrifugation and washing. The mass of yeast milk was weighed, i.e., biomass, and moisture was tested. The dry weight and relative percentage were calculated. The results are shown in Table 3. The relative percentage was calculated as follows:

[0077] Dry weight (g / L) = yeast milk mass * (1-water content)

[0078] Relative percentage = (hybrid strain dry weight / parent strain AMCC30002 dry weight) * 100%

[0079] Table 3 Biomass dry weight (g / L) and relative percentage (%) of hybrid strains

[0080]

[0081] As shown in Table 3, the dry weight of the biomass of the Saccharomyces cerevisiae AMCC 31195 provided by the present invention can reach 13.32 g / L after overnight culture in a shake flask.

[0082] Embodiment 3

[0083] The fermentation activity of Saccharomyces cerevisiae AMCC 31195 strain and the parent strains Saccharomyces cerevisiae AMCC 30002 strain and Saccharomyces cerevisiae AMCC30004 strain were tested in test A and test B. Test A: 16% sugar dough system; Test B: 16% sugar + 1% calcium propionate dough system. The percentage of baking raw materials in the dough systems of test A and test B is shown in Table 4 below. The weight of the required yeast milk is calculated. Test A tests the fermentation activity of 280g dough for 1h, and test B tests the fermentation activity of 70g dough for 3h. The results are shown in Table 5. The calculation method of the relative activity percentage in Table 5 is as follows:

[0084] Relative activity percentage = (fermentation activity of hybrid strain / parent strain AMCC30002) * 100%

[0085] Table 4 Formula of dough system of test A and test B

[0086]

[0087] Table 5 Fermentation activity (mL) and relative activity percentage (%) of hybrid strain test A and test B

[0088]

[0089] As shown in Table 5, the AMCC 31195 strain of Saccharomyces cerevisiae provided by the present invention produces 667 ml of gas in 16% sugar dough system 280 g dough fermentation for 1 hour, and produces 621 ml of gas in 16% sugar + 1% calcium propionate dough system 70 g dough fermentation for 3 hours.

[0090] Embodiment 4

[0091] The cerevisiae AMCC 31195 strain and the parent strains of cerevisiae AMCC 30002 strain and cerevisiae AMCC 30004 strain were inoculated into YPD liquid medium for 30L fermentation tank culture, and the active dry yeast was obtained by separation, washing, suction filtration, filter pressing, granulation, drying and packaging, and then the fermentation activity of 280g dough was tested for test C, and the test time was 2h. Test C: 16% sugar + 0.6% calcium propionate dough system, the percentage of baking raw materials is shown in Table 6 below, and the test results are shown in Table 7. The calculation method of the relative activity in Table 7 is as follows:

[0092] Relative activity = (fermentation activity of hybrid strain / fermentation activity of parent strain AMCC 30002) * 100%

[0093] Table 6 Baking raw material formula of test C dough system

[0094]

[0095] Table 7 Fermentation activity (mL) and relative activity percentage (%) of hybrid strain test C

[0096]

[0097]

[0098] As shown in Table 7, the active dry yeast prepared from the AMCC 31195 strain of Saccharomyces cerevisiae provided by the present invention produces 955 ml of gas when 280 g of dough is fermented for 2 hours in a 16% sugar + 0.6% calcium propionate dough system.

[0099] Embodiment 5

[0100] Active dry yeast of Saccharomyces cerevisiae AMCC 31195 strain and active dry yeast of parent strain Saccharomyces cerevisiae AMCC30002 strain and active dry yeast of Saccharomyces cerevisiae AMCC 30004 strain were used to prepare 400g dough of 6 application formulas shown in Table 8. The parent strain AMCC30002 with more advantageous properties was selected as the control strain. The fermentation time was used as an indicator. The shorter the fermentation time, the faster the dough rises under the same volume, and the yeast strain has more advantageous properties. The percentage of baking raw materials in each application formula is shown in Table 8 below (the water in formula 4 is 0℃ crushed ice for experiment); Formula 1: 15% sugar + 0.3% calcium propionate dough system; Formula 2: 20% sugar dough system; Formula 3: 20% sugar + 0.5% calcium propionate dough system; Formula 4: 20% sugar cold osmotic shock dough system; Formula 5: 25% sugar + 0.6% calcium propionate dough system; Formula 6: 40% sugar + 20% butter dough system. The results are shown in Table 9. Among them, the calculation method of the percentage of fermentation time relative to the control strain in Table 9 is as follows:

[0101] Percentage of fermentation time relative to control strain = (fermentation time of hybrid strain / fermentation time of parent strain AMCC30002)*100%

[0102] Table 8 Application formula baking raw material formula

[0103]

[0104]

[0105] Table 9 Application test fermentation time and relative percentage (%)

[0106]

[0107] As shown in Table 9, the AMCC 31195 strain of Saccharomyces cerevisiae has trait advantages in all six application formulas, indicating that the strain can grow normally in a 15-40% sugar dough system and has high sugar osmotic pressure resistance; the advantages shown in Formula 1, Formula 3, and Formula 5 indicate that its organic acid resistance is stronger than that of the AMCC 30002 strain; the advantage is most obvious in Formula 4, and the fermentation time is 5.7% faster than that of the AMCC 30002 strain, indicating that it has cold osmotic shock resistance; in Formula 6, the fermentation time is 4.7% faster than that of the AMCC30002 strain, indicating that it has tolerance in the heavy oil and heavy sugar system and can meet the application requirements of heavy oil and heavy sugar products.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A Saccharomyces cerevisiae strain, characterized in that: The saccharomyces cerevisiae strain is: Saccharomyces cerevisiae Saccharomyces cerevisiae )AMCC 31195 strain, which is deposited in China Center for Type Culture Collection (CCTCC) with the deposit number CCTCC NO: M 20211685.

2. A fermentation method for preparing a brewer's yeast inoculant, characterized in that: The method comprises the following steps: culturing the Saccharomyces cerevisiae strain according to claim 1.

3. The preparation method according to claim 2, characterized in that: The preparation method comprises the following steps: (1) Cultivating the Saccharomyces cerevisiae strain described in claim 1; (2) Add the product obtained in step (1) into liquid culture medium and ferment at 26-32°C.

4. A bacterial agent, characterized in that: The bacterial agent contains the brewer's yeast according to claim 1 ( Saccharomyces cerevisiae ) AMCC 31195 strain.

5. The bacterial agent according to claim 4, characterized in that The bacterial agent is obtained by the fermentation preparation method according to claim 2 or 3.

6. Use of the cerevisiae yeast strain according to claim 1 or the bacterial agent according to claim 4 or 5 in fermentation.

7. Use of the saccharomyces cerevisiae strain according to claim 1 or the bacterial agent according to claim 4 or 5 in dough.

8. A dough, characterized in that: The dough contains the brewer's yeast strain according to claim 1 or the bacterial agent according to claim 4 or 5.

9. The dough according to claim 8, characterized in that The dough contains flour and the brewer's yeast strain in a mass ratio of 100:0.5-5.

10. The dough according to claim 8, characterized in that The dough contains sucrose, and the dough contains flour and sucrose in a mass ratio of 100:15-40.

11. The dough according to claim 9, characterized in that The dough contains sucrose, and the dough contains flour and sucrose in a mass ratio of 100:15-40.

12. The dough according to claim 8, characterized in that The dough contains flour and sucrose in a mass ratio of 100:16-40.

13. The dough according to claim 9, characterized in that The dough contains flour and sucrose in a mass ratio of 100:16-40.

14. The dough according to any one of claims 8 to 13, characterized in that The dough also contains a preservative.

15. The dough according to claim 14, characterized in that The preservative is an organic acid and its salt preservative.

16. The dough according to claim 15, characterized in that The organic acid is propionic acid, and the organic acid salt is one or both of calcium propionate and sodium propionate.

17. The dough according to any one of claims 8 to 13, characterized in that The dough contains a preservative, and the mass ratio of flour to the preservative in the dough is 100:0-1.

18. The dough according to claim 17, characterized in that The preservative is an organic acid and its salt preservative.

19. The dough according to claim 18, characterized in that The organic acid is propionic acid, and the organic acid salt is one or both of calcium propionate and sodium propionate.

20. The dough according to claim 17, characterized in that The mass ratio of flour to preservative in the dough is 100:0-0.

6.

21. The dough according to claim 18, characterized in that The mass ratio of flour to preservative in the dough is 100:0-0.

6.

22. The dough according to claim 19, characterized in that The mass ratio of flour to preservative in the dough is 100:0-0.

6.

23. The method for preparing dough according to any one of claims 8 to 22, characterized in that: The preparation method comprises the following steps: kneading flour with water at 0-35°C.

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