Bacillus velezensis and application thereof

Abstract

The invention relates to the technical field of microorganisms, in particular to bacillus velezensis and application thereof, and provides bacillus velezensis B5 and application thereof, the preservation number of the bacillus velezensis B5 is CCTCC NO: M 20241698, and the bacillus velezensis B5 is obtained through separation and purification from high-temperature yeast produced by Hubei Jianbrand Co., Ltd. The bacillus velezensis B5 provided by the invention has good ethyl carbamate degradation capacity, can be used for brewing Maotai-flavor Daqu liquor when being prepared into a microbial agent, can reduce the content of ethyl carbamate in raw liquor by 28%-41%, can increase the content of total ester and total acid in the raw liquor, and effectively improves the quality of the liquor.

Description

Technical Field

[0001] The invention relates to the technical field of microorganisms, in particular to Bacillus Velezii and application thereof. Background Art

[0002] Ethyl carbamate (EC), also known as urethane and urethane, is a Class 2A carcinogen with potential genotoxicity and is commonly found in traditional fermented foods and alcoholic beverages (baijiu, wine, rice wine, etc.). Chinese baijiu and other distilled liquors metabolize to produce ethyl carbamate during the fermentation process of grains by microorganisms. As one of the indispensable representatives of my country's food culture, the quality and safety of baijiu are closely related to the health of the people. At present, a large number of studies have shown that the EC content in fermented foods can be controlled mainly through production process optimization, biodegradation (enzymatic hydrolysis and microbial degradation), etc. Among them, the screening of functional strains with high EC degradation activity has always been one of the research hotspots in the field of EC control and one of the most effective control methods. Therefore, screening and obtaining functional microbial strains with EC degradation activity from the brewing environment plays an extremely important role in improving the flavor and health connotation of Chinese baijiu.

[0003] At present, the content of ethyl carbamate in the brewing process is controlled by microbial functional strains, which are mostly concentrated in wine, sake and rice wine. The performance of the strains is modified by bioengineering means to reduce the generation of ethyl carbamate and its precursors. At present, in the patent application with publication number CN113913314A, a cerevisiae strain G2 that reduces the accumulation of urea and ethyl carbamate in rice wine is provided. In 2024, three recombinant engineering strains YCG11, YCG21 and YVA11 constructed by Fan Linlin et al. through gene knockout and gene recombination technology have good activity in reducing ethyl carbamate in the wine brewing process. However, this technology is difficult to apply to the brewing of liquor with complex fermentation microbial systems. Therefore, a homologous strain that can degrade EC is obtained by culture group methods, and it begins to be used in the effective reduction and control of EC and its precursor (urea) in liquor. Patent application with publication number CN112226394A discloses a strain of Bacillus amyloliquefaciens, which can effectively reduce the content of ethyl carbamate in Luzhou-flavor liquor, but the huge differences in the brewing processes of different flavor liquors make it difficult to apply the strain across flavors. Patent application with publication number CN115287203A discloses a strain of red yeast DL-XSY01, which can be prepared into an EC degradation preparation and added to the finished raw liquor, which can effectively reduce EC in Maotai-flavor liquor, but there is a risk of affecting other flavor components of the liquor due to the additional treatment, and at the same time, the corresponding cost is incurred when the processed raw liquor is recycled.

[0004] Therefore, it is necessary to screen EC-degrading functional strains that can be applied to the brewing of Maotai-flavor liquor, reduce the EC content without affecting other flavors, improve the quality of Maotai-flavor liquor, and provide consumers with healthier liquor products. Summary of the invention

[0005] In view of this, the present invention provides a strain of Bacillus Velezii, which has high activity in degrading ethyl carbamate.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a strain of Bacillus velezensis, which is classified and named Bacillus velezensis B5, and the strain is preserved in the China Center for Type Culture Collection, the preservation date is July 31, 2024, the preservation number is CCTCC NO: M 20241698, and the preservation address is: China Center for Type Culture Collection, Luojiashan, Bayi Road, Wuchang District, Wuhan City, Hubei Province, Postal Code: 430072.

[0007] The bacteriological characteristics of the Bacillus velezensis B5 are as follows: the colonies are milky white, opaque, rough in surface, and smooth and neat at the edges. The bacterial cells are rod-shaped, 2.6-5.2 μm long, 0.5-1.0 μm wide, without capsule, and with spores in the middle. It is Gram-positive.

[0008] The Bacillus velezensis B5 is obtained according to the following method:

[0009] The high-temperature Daqu of Hubei Jingpai Co., Ltd. was used as the source of microbial screening for the degradation of ethyl carbamate. First, strains were screened from the high-temperature Daqu and inoculated into characteristic plate culture to select active strains that can degrade ethyl carbamate, and then inoculated into liquid fermentation medium. After the fermentation was completed, the content of ethyl carbamate in the fermentation liquid was measured to screen out the strain with the highest activity in degrading ethyl carbamate. Finally, it was mixed with the sauce-flavored Daqu in proportion to form a mixed song, and pure sauce-flavored Daqu was used as the control song to brew and produce sauce-flavored liquor. After distillation, ethyl carbamate and other main quality indicators were compared.

[0010] The second aspect of the present invention is to provide the use of Bacillus velezensis B5 for degrading ethyl carbamate.

[0011] Specifically, it can be used to degrade ethyl carbamate in liquor.

[0012] In some embodiments, the liquor is a sauce-flavor liquor.

[0013] In some embodiments, Bacillus velez yeast is used to degrade ethyl carbamate in liquor.

[0014] In some embodiments, the Bacillus velezensis yeast is obtained by mixed fermentation of Bacillus velezensis B5 and Shennongjia Maotai-flavor Daqu.

[0015] The third aspect of the present invention is to provide a microbial agent, which contains Bacillus velezensis B5 with a deposit number of CCTCCNO: M 20241698.

[0016] In some embodiments, the microbial agent is a solid agent or a liquid agent.

[0017] The fourth aspect of the present invention is to provide a liquor brewed from a microbial agent comprising Bacillus velezensis B5 with a preservation number of CCTCCNO: M20241698.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The Bacillus velezensis B5 of the present invention can achieve 84% degradation of ethyl carbamate by inoculating liquid fermentation. It is prepared into a microbial agent and applied to the brewing of Maotai-flavor Daqu liquor, which can reduce the ethyl carbamate content in the original liquor by 28%-41%, and at the same time increase the content of total ester and total acid in the original liquor, effectively improving the quality of the liquor. The strain is a homologous strain separated from the koji, can be used for liquor production, and provides a new safe and reliable functional strain for improving the quality of Maotai-flavor Daqu liquor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a graph showing the content of ethyl carbamate in the Maotai-flavor liquor obtained in Example 1 of the present invention;

[0022] Figure 2 This is a graph showing the contents of esters and acids in the Maotai-flavor liquor obtained in Example 1 of the present invention;

[0023] Figure 3 This is the microscopic morphology of the B5 strain under a microscope (10×100);

[0024] Figure 4 This is a graph showing the growth of strain B5 at different ethanol concentrations;

[0025] Figure 5 This is a graph showing the growth of strain B5 at different NaCl concentrations;

[0026] Figure 6 This is a graph showing the growth of strain B5 at different pH levels;

[0027] Figure 7 This is a graph showing the growth of strain B5 at different temperatures;

[0028] Figure 8 This is a graph showing the growth of strain B5 under different glucose contents. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the embodiments of the present invention belong. If the definitions set forth in this section are contrary to or otherwise inconsistent with the definitions set forth in the patents, patent applications, published patent applications, and other publications incorporated herein by reference, the definitions listed in this section take precedence over the definitions incorporated herein by reference.

[0031] Unless otherwise specified, the methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents and instruments used are all conventional materials, reagents and instruments in the art, and can be obtained by those skilled in the art through commercial channels.

[0032] When an amount, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range. In the present specification and claims, range definitions can be combined and / or interchanged, and if not otherwise stated, these ranges include all subranges contained therein.

[0033] The Bacillus velezensis B5 provided by the present invention was deposited in the China Center for Type Culture Collection (CCTCC) on July 31, 2024, with a deposit number of CCTCC NO: M 20241698, and the deposit address is: China Center for Type Culture Collection, Luojiashan, Bayi Road, Wuchang District, Wuhan City, Hubei Province, Postal Code: 430072.

[0034] The 16S rDNA sequence of Bacillus velezensis B5 is shown in Table 1.

[0035] Table 1 Phylogenetic information of strains and their 16S rDNA amplification sequence results

[0036]

[0037] The bacteriological characteristics of Bacillus velezensis B5 are as follows: the colonies are milky white and opaque, with a rough surface and smooth and neat edges. The bacterial cells are rod-shaped, 2.6-5.2 μm long and 0.5-1.0 μm wide, without capsule, and with spores in the middle. It is Gram-positive.

[0038] The culture method of Bacillus velezensis B5 comprises the following steps: inoculating Bacillus subtilis into an LB liquid culture medium with the components of 10g sodium chloride, 10g peptone, 5g yeast extract powder, 1000ml water and pH=5-8, and culturing at 37°C and 150-160r / min for 24-48 hours.

[0039] The Bacillus velezensis B5 was isolated from the high temperature Daqu of Jinpai Co., Ltd.

[0040] Example 1

[0041] Screening of functional strains for degrading ethyl carbamate

[0042] 1. Isolation and screening of high temperature Daqu bacteria from Hubei Jinpai Co., Ltd.

[0043] Material: High temperature Daqu from Hubei Jinpai Co., Ltd.

[0044] Culture medium:

[0045] LB medium: 10 g sodium chloride, 10 g peptone, 5 g yeast extract powder, 1000 ml water, pH = 7.0. Bottle and sterilize in an autoclave at 121°C for 20 minutes, cool and set aside.

[0046] Bacterial isolation and purification: Take 10g of koji sample and add it to 90ml of sterile distilled water, put it into a shaker at 160r / min for 30min, then perform gradient dilution, take 200μL of 10 -6 and 10 -7 Two gradients of bacterial suspension were added to LB solid culture medium for coating, and then placed in a 37°C incubator for culture observation. The bacterial colonies on the plate were observed and screened, and bacterial colonies with different morphologies were picked for purification and culture for the next step of experimental screening.

[0047] 2. Screening of functional strains for degrading ethyl carbamate

[0048] 2.1 Preliminary screening of ethyl carbamate degradation

[0049] Experimental strains: bacterial strains isolated from the distiller's yeast of Hubei Jinpai Co., Ltd.

[0050] Screening medium: 10g sodium chloride; 10g tryptone; 5g yeast extract powder; 5g ethyl formate; 5mg bromocresol purple; 1000ml water; pH = 7.0. Add 1000ml water and heat to dissolve. Bottle and sterilize in a 121℃ autoclave for 20 minutes, cool and set aside.

[0051] Experimental methods:

[0052] (1) Activation of bacterial strains and preparation of seed solution: 100 μL of bacterial solution in a glycerol storage tube was transferred into 10 mL of LB liquid medium and cultured in a shaking incubator at 30°C and 160 r / min for 24 h. A small amount of the culture solution was streaked on an LB plate and cultured in an inverted incubator at 37°C for 24 h. A loop of a single colony was taken and inoculated into LB liquid medium and cultured in a shaking incubator at 37°C and 160 r / min for 24 h to obtain seed solution, which was refrigerated for later use.

[0053] (2) Qualitative analysis of the activity of strains in degrading ethyl carbamate: The strains isolated from Daqu were activated and inoculated onto screening culture plates and cultured at 37°C. The growth of the strains on the plates was observed, and the strains that changed the color of the culture medium from yellow to purple were selected as the strains for subsequent quantitative screening. A total of ten functional strains with the activity of degrading ethyl carbamate were screened out, named B1-B10.

[0054] (3) Quantitative analysis of the activity of strains in degrading ethyl carbamate: Add water to the sorghum juice medium to adjust the sugar content to °Bx8, dispense 50mL into a 250mL conical flask, and add ethyl carbamate to make the final concentration 3g / L, sterilize at 121℃ for 20min. Take the activated seed liquid and inoculate it into the culture medium at an inoculation rate of 1% (v / v), and ferment and culture at 37℃ and 160r / min for 7 days. After the fermentation is completed, take the fermentation liquid, centrifuge it at 5000r10min, take the supernatant, pass it through a 0.45μm filter membrane, and filter the fermentation supernatant for gas chromatography analysis. Select the strain with the highest rate of degrading ethyl carbamate for the next step of solid-state fermentation verification.

[0055] Gas chromatography results showed that among the 10 screened Bacillus strains, B5 had the highest efficiency in degrading ethyl carbamate, with an ethyl carbamate content of 470.45 mg / L in its fermentation broth (the ethyl carbamate concentration in the culture medium before fermentation was 3 g / L), and an EC degradation efficiency of 84%.

[0056] 2.2 Laboratory test of ethyl carbamate degradation strains

[0057] Experimental methods:

[0058] Preparation of test bacterial agent: a) Preparation of pure solid bacterial agent of strain B5: add 60% water to 1 kg of bran, stir evenly, sterilize and set aside; inoculate the Bacillus velezensis B5 seed liquid with the deposit number of CCTCC NO: M 20241698 into the bran culture medium, culture at 37°C for 48 hours, and then dry to prepare the B5 bran pure bacterial agent. b) Preparation of pure liquid bacterial agent of strain B5: take a loop of single colony and inoculate it into LB liquid culture medium, culture it in a shaking table at 37°C and 160r / min for 24 hours to obtain liquid bacterial agent. c) Preparation of test mixed koji of Bacillus velezensis B5: mix the pure bacterial agent of B5 with Daqu at a mass ratio of 15:100 or a volume mass ratio of 15:100.

[0059] (2) Mixing grain koji: 20 kg of grain dregs from the previous round of fermentation and the addition of new grain for brewing wine are cooled to 20-30° C. 1.2 kg of the experimental mixed koji prepared in step 1 with Bacillus Velez B5 is added and mixed thoroughly.

[0060] (3) Stacking and fermentation: The fully mixed grains are placed in the fermentation chamber and drying hall for stacking at room temperature, and the stacking and fermentation are carried out for 72-96 hours respectively.

[0061] (4) Cellar fermentation: The grain that has finished piling up is placed in an underground cellar for flavor fermentation. The entire cellar fermentation stage lasts about 30 days.

[0062] (5) Taking wine: The fermented mash is placed in a distillation retort for heating and distillation. 200 ml of the distilled wine is sampled and the ethyl formate and related flavor chromatographic index parameters in the wine are determined using liquid chromatography-mass spectrometry and gas chromatography detection technology.

[0063] (6) Ethyl carbamate detection method: Accurately transfer 0.95 mL of the original wine sample into a 2 mL sample bottle, add 50 μL of internal standard solution, and shake well. Place in an 80℃-90℃ oven to remove ethanol, and take out and cool when the liquid in the bottle is reduced to 0.4-0.5 mL. Add water to make the volume 1 mL, filter with a 0.45 μm water filter membrane, and then detect on the machine. The HPLC mass spectrometry conditions are: Water ACQUITY TQD triple quadrupole LC-MS instrument, Xselect HSS T3 chromatographic column (3.5 μm, 2.1×100 mm). Program parameters: gradient elution with acetonitrile and -0.1% formic acid aqueous solution, flow rate 0.3 mL / min, column temperature 40℃, injection volume 10 μL. The ion source mode was ESI+; the nebulizer temperature was 400°C; the ion source temperature was 150°C; the capillary voltage was 3kv; the nebulizer gas flow rate was 800L / h; the cone gas flow rate was 100L / h; and the collision gas flow rate was 0.17mL / min.

[0064] (7) Chromatographic detection of raw liquor: Take 1 mL of raw liquor in a 2 mL sample bottle, add 10 μL of mixed internal standards (tert-amyl alcohol (IS1): 160.095 mg / L, n-amyl acetate (IS2): 176.213 mg / L, 2-ethylhexanol (IS3): 163.342 mg / L), shake well, and use gas chromatography to determine the content of each component in the raw liquor. The chromatographic conditions are: Agilent 780A gas chromatograph, detector FID, CP-WAX capillary column (50m×0.2μm×0.25mm). Temperature program: column temperature is maintained at 40°C for 8 minutes, and then increased to 150°C at 5°C / min. The injection port temperature is 250°C, the detector temperature is 260°C, the air and hydrogen flow rate ratio is 300:30, the carrier gas is nitrogen, the split ratio is 30:1, and the column flow rate is 1.0 mL / min. The test results are shown in Figure 1 and Figure 2 .

[0065] The test results of adding solid pure strains showed that the EC content in the original wine of the experimental group was 111.28μg / L, and that of the control group was 154.72μg / L. It can be seen that adding strains can effectively reduce the EC content by 28%. In terms of conventional flavor substances, the total content of 19 esters in the original wine of the experimental group was 5.8g / L, and the total content of 9 acids was 2.8g / L, which were increased by 84% and 53% respectively compared with the control group.

[0066] The results of adding liquid pure strain bacterial agent: the EC content in the experimental group was 120.29μg / L, and that in the control group was 206.13μg / L. The addition of strains could reduce the EC content by 41.6%. In terms of conventional flavor substances, the total content of 19 esters in the original liquor of the experimental group was 7.31g / L, and the total content of 9 acids was 4.46g / L, which were increased by 0.2% and 0.8% respectively compared with the control group.

[0067] Example 2

[0068] Phylogenetic analysis of strain B5

[0069] 1. 16S rDNA sequence analysis

[0070] (1) DNA extraction

[0071] Collect bacteria and use DNA was extracted using a soil genomic DNA extraction kit. The specific method was referred to its instruction manual.

[0072] (2) Amplification of 16S rDNA fragment of strain B5

[0073] The extracted DNA of strain B5 was used as a template, and the bacterial 16S rDNA universal primers 27F and 1492R were used to amplify the 16S rDNA fragment. The amplification reaction system was 30μL, including 15μL of Premix TaqTM (TaKaRa TaqTM Version 2.0plusdye), 13μL of ddH2O, 0.5μL of primers 27F and 1492R, and 1μL of DNA template. Amplification reaction conditions: 94℃5min; 94℃30s; 52℃50s, 72℃30s, 32 cycles; 72℃ extension for 10min, 4℃ storage.

[0074] (3) 16S rDNA sequence analysis

[0075] The amplified 16S rDNA fragments were sent to Guangzhou BGI for sequencing, and the corresponding 16S rDNA amplification sequence results were obtained (as shown in Table 1). The species information was obtained by comparison through the Blast search program of the National Center for Biotechnology Information (NCBI) (as shown in Table 1).

[0076] 2. Morphological characteristics and tolerance test of Bacillus Velezii B5

[0077] The bacteria used in the following experiments were activated by inoculation with LB solid medium and cultured at 37°C for 1-3 days before use in the following experiments:

[0078] (1) Microscopic observation of colonies and bacteria

[0079] Observe the colony morphology of Bacillus Velezii B5 on the LB medium plate under 37°C culture conditions; use an inoculation needle or a sterilized toothpick to pick up a small amount of bacteria and place it on a slide, and observe the bacteria under a microscope (10×100). The observation results are as follows: The colonies are milky white, opaque, with a rough surface and smooth and neat edges. The bacterial cells are rod-shaped, 2.6-5.2μm long, 0.5-1.0μm wide, without capsule, and with spores. The specific morphology is as follows: Figure 3 .

[0080] (2) Ethanol resistance test

[0081] The ethanol concentration of LB liquid culture medium was adjusted to 0%, 2%, 4%, 6%, 8%, 10%, and 12% (v / v) with anhydrous ethanol, and B5 bacterial seed liquid was inoculated at a 1% inoculation amount. After culturing at 37°C and 160 r / min for 24 hours, the absorbance was measured at a wavelength of 600 nm. The test results are shown in Figure 4 .

[0082] Since the liquor brewing process produces ethanol, it will inhibit bacterial cell metabolism to a certain extent, causing bacterial growth to stagnate or die. Figure 4 It can be seen that with the increase of ethanol content, the growth of strains is inhibited. All strains can tolerate 6% ethanol content, and then with the increase of ethanol content, the biomass of strains decreases significantly. However, the ethanol concentration in the fermented grains does not exceed 6% during the fermentation process, so the B5 strain can tolerate the increase of ethanol content during the fermentation of liquor.

[0083] (3) High salt resistance test

[0084] The salt content of LB liquid culture medium was adjusted to 0%, 2%, 4%, 6%, 8%, 11%, and 14% (m / v) with NaCl, and B5 bacterial seed solution was inoculated at a 1% inoculation rate. After culturing at 37°C and 160 r / min for 24 h, the absorbance was measured at a wavelength of 600 nm. The test results are shown in Figure 5 .Depend on Figure 5 It can be seen that as the NaCl content increases, the biomass of bacteria B5 decreases. The strain B5 can tolerate a maximum salt content of 8%, and when the NaCl content reaches 11%, the strain has no growth.

[0085] (4) Acid resistance test

[0086] The pH of the LB liquid medium was adjusted to 3, 4, 5, 6, 7, 8, and 9 with 0.1 mol / L HCl and 0.1 mol / L NaOH, and the B5 bacterial seed solution was inoculated at 1% inoculation amount. After culturing at 37°C and 160 r / min for 24 h, the absorbance was measured at a wavelength of 600 nm. The test results are shown in Figure 6 During the fermentation process of sorghum, acid will continue to be produced, resulting in a low pH in the fermented grains. Therefore, the ability to tolerate an acidic environment plays an important role in the function of the strain in the liquor brewing process. Figure 6 As shown, strain B5 can grow well under pH conditions of 5-8 and can adapt to the acidic environment of fermented grains.

[0087] (5) High sugar tolerance test

[0088] Glucose was added to LB liquid culture medium to make its sugar concentration 10%, 20%, 30%, 40%, 50%, 60% (m / v), and B5 bacterial seed liquid was inoculated at 1% inoculation amount. After culturing at 37℃ and shaking at 160r / min for 24h, the absorbance was measured at a wavelength of 600nm. The test results are shown in Figure 7 .from Figure 7 It can be seen that high concentration of glucose will seriously affect the activity of bacterial cells. As the glucose content increases, the bacterial biomass decreases, and the biomass is the highest at 10% glucose concentration. The B5 strain can tolerate up to 20% glucose content.

[0089] (6) Temperature resistance test

[0090] Inoculate 1% of B5 bacterial seed solution into LB liquid culture medium, incubate at 15℃, 25℃, 30℃, 37℃, 45℃, 50℃ for 24h, and measure the absorbance at 600nm. The test results are shown in Figure 8 .from Figure 8 It can be seen that when the temperature drops below 15°C, the biomass of the B5 strain decreases significantly. As the temperature rises, the biomass of the B5 strain begins to increase significantly, and the strain grows better at a culture temperature of 25-45°C.

[0091] 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 principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A strain of Bacillus Velez, characterized in that: The classification name is Bacillus velezensis B5. The strain is deposited in the China Center for Type Culture Collection on July 31, 2024, and the deposit number is CCTCC NO: M20241698.

2. Use of Bacillus Velezii as claimed in claim 1 in degrading ethyl carbamate.

3. Use of Bacillus Velezii as claimed in claim 2 in degrading ethyl carbamate in liquor.

4. The use according to claim 3, characterized in that The liquor is a sauce-flavor liquor.

5. The use according to claim 3, characterized in that Bacillus velez yeast was used to degrade ethyl carbamate in liquor.

6. The use according to claim 5, characterized in that The Bacillus Velez yeast is obtained by mixed fermentation of Bacillus Velez and Shennongjia Maotai-flavor Daqu.

7. A microbial agent for degrading ethyl carbamate in liquor, comprising the Bacillus Velezii with a deposit number of CCTCC NO: M20241698 as claimed in claim 1.

8. The microbial agent according to claim 7, characterized in that The microbial agent is a solid agent or a liquid agent.

9. A liquor, characterized in that: The brewery is brewed from a microbial agent comprising the Bacillus Velezii with a deposit number of CCTCC NO: M 20241698 as described in claim 1.

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