Lactobacillus plantarum, lactobacillus plantarum microbial preparation as well as preparation method and application of lactobacillus plantarum microbial preparation

Abstract

The invention provides lactobacillus plantarum, a lactobacillus plantarum microbial preparation and a preparation method and application of the lactobacillus plantarum microbial preparation, and belongs to the technical field of microorganisms. The invention provides the lactobacillus plantarum HRB1pMG36e-luxS, and the lactobacillus plantarum HRB1pMG36e-luxS is prepared into a biological agent through the provided preparation method. The invention discloses lactobacillus plantarum L.plantarum HRB1pMG36e-luxS and a biological agent of the lactobacillus plantarum L.plantarum HRB1pMG36e-luxS, and the biological agent of the lactobacillus plantarum L.plantarum HRB1pMG36e-luxS is mainly applied to preparation of air-dried sausages. The lactobacillus plantarum HRB1pMG36e-luxS quorum sensing signal molecule AI-2 is high in expression quantity and has the capability of remarkably improving the activity of protease and lipase, the activity of intracellular protease is 16.23 U / mL protein, the activity of intracellular lipase is 14.24 U / mL, the problem of product difference caused by different environmental factors in the fermentation process is solved, and the quality, flavor and safety of the air-dried sausages are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of microorganisms, and particularly relates to application of Lactobacillus plantarum HRB1pMG36e-luxS and a biological preparation thereof in preparing air-dried sausages. Background Art

[0002] Air-dried sausage is a traditional fermented meat product, which is deeply loved by consumers for its unique taste and flavor. Traditional air-dried sausage is made of lean pork, pork back fat, salt, nitrite, Daqu and various spices mixed into sausage casings. The fermentation and maturation of traditional air-dried sausage is achieved through the action of endogenous enzymes and microbial communities in a natural state. In this process, the formation of flavor mainly depends on the enzymatic degradation of macromolecules such as lipids, proteins and carbohydrates by microorganisms in the system. However, the microbial community in a natural state can lead to unstable quality.

[0003] Lactic acid bacteria are commonly used as starter cultures in the processing of fermented foods. Lactic acid bacteria can enhance flavor through three key metabolic pathways: carbohydrate metabolism, proteolysis and amino acid decomposition, and lipolysis and fatty acid metabolism. In addition, lactic acid bacteria can reduce the pH of the system by metabolizing lactic acid or produce bacteriocins, which inhibit spoilage microorganisms. Therefore, regulating lactic acid bacteria metabolism is of great significance to improving the flavor, shelf life and nutritional value of fermented meat products.

[0004] Certain lactic acid bacteria communicate through specific signaling molecules during their growth, allowing cells to sense the abundance of their own species in the surrounding environment and regulate gene expression accordingly, thereby promoting communication within species and genera. This phenomenon in which strains regulate gene expression by sensing changes in the density of similar cells around them is called quorum sensing. Under natural or artificial controlled conditions, fermented powder meat products made by microbial fermentation significantly increase microbial diversity during the natural fermentation process, but due to differences in environment, climate, equipment and fermentation agents, microbial differences are large, and the safety of fermentation and the quality of the final product are difficult to control. Therefore, the consistency and safety of the quality of different batches of traditional air-dried sausages and how to improve the flavor of fermented meat products are hot issues that need to be addressed urgently. Summary of the invention

[0005] The invention solves the problem of product differences caused by different environmental factors during the fermentation process by constructing Lactobacillus plantarum HRB1 pMG36e-luxS and preparing a Lactobacillus plantarum HRB1 pMG36e-luxS biological preparation, thereby improving the quality, flavor and safety of air-dried sausages.

[0006] The invention provides a lactobacillus plantarum HRB1 pMG36e-luxS.

[0007] The plant lactobacillus is obtained by transforming plasmid pMG36e-luxS into L. plantarum HRB1.

[0008] The invention provides an application of L. plantarum HRB1 pMG36e-luxS in preparing air-dried sausage.

[0009] The invention provides a microbial preparation of Lactobacillus plantarum, which is prepared by adopting L. plantarum HRB1pMG36e-luxS.

[0010] The invention provides a method for preparing a microbial preparation of Lactobacillus plantarum. The preparation method comprises the following steps: activating L. plantarum HRB1 pMG36e-luxS, discarding the supernatant by centrifugation to obtain active bacterial mud, then mixing the active bacterial mud with a skim emulsion and culturing the mixture, and then pre-freezing the cultured active bacterial mud and the skim emulsion, and then placing the mixture in a vacuum freeze dryer for freeze drying after the pre-freezing is completed.

[0011] The concentration of bacteria in the active bacterial sludge is 10 6 -10 7 CFU / g.

[0012] The active bacterial mud and the skimmed emulsion are mixed at a mass ratio of 1:10.

[0013] The active bacterial sludge and the skimmed emulsion are mixed and cultured at 37° C. for 2 hours.

[0014] The pre-freezing is pre-freezing in a -40°C refrigerator for about 5-7 hours.

[0015] The invention provides application of a Lactobacillus plantarum microbial preparation in preparing air-dried sausages.

[0016] Beneficial Effects

[0017] Lactobacillus plantarum HRB1 pMG36e-luxS has a high expression level of the quorum sensing signal molecule AI-2, which has the ability to significantly increase the activity of proteases and lipases (P<0.05). The intracellular protease activity is 16.23U / mL protein, and the intracellular lipase activity is 14.24U / mL. It can be used as a flavor-producing starter in the production of fermented meat products. In addition, the biological preparation prepared by Lactobacillus plantarum HRB1pMG36e-luxS can reduce the differences in products caused by different environmental factors during the fermentation process and improve the quality, flavor and safety of air-dried sausages. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Construction process and verification gel image for Lactobacillus plantarum HRB1 pMG36e-luxS.

[0019] Figure 2 The results of the ability of different strains to produce the signal molecule AI-2 are shown in Figure 2.

[0020] Figure 3 The results of protease activity of different strains are shown in Figure 2.

[0021] Figure 4 The results of lipase activity of different strains are shown in Figure 2. DETAILED DESCRIPTION

[0022] Strains used in the experiments.

[0023] Lactobacillus plantarum HRB1: Technical characterization and flavor-producing potential of lactic acid bacteria isolated from traditional dryfermented sausages in northeast China. (FoodMicrobiology.106(2022)104059)

[0024] Example 1. Method for constructing an engineered strain overexpressing the luxS gene.

[0025] 1. Obtaining pMG36e-luxS.

[0026] Using the genome of Lactobacillus plantarum HRB1 as a template, the luxS gene was amplified by PCR using the primers luxS-up and luxS-down in Table 1. The sequence is shown in SEQ1. The reaction system and reaction conditions of PCR are as follows:

[0027] Table 1 Primer sequences used

[0028]

[0029] The luxS PCR reaction system is: 25 μL of 2×PhantaMax Buffer, 1 μL of dNTP Mix (10 mM), 2 μL each of upstream primer luxS-up and downstream primer luxS-down (10 μM), 0.5 μL of template, 1 μL of Phanta Max Super-Fidelity DNA Polymerase, and sterile water to a final volume of 50 μL.

[0030] The PCR reaction conditions were as follows: pre-denaturation at 95°C for 3 min, denaturation at 95°C for 15 s, annealing at 52°C for 12 s, extension at 72°C for 14 s, 35 cycles, and post-extension at 70°C for 5 min.

[0031] The construction scheme of the recombinant plasmid pMG36e-luxS is as follows Figure 1 A, the obtained vector pMG36e (such as Figure 1 B, purchased from Miaoling Biotechnology) was double-digested with XbaI and HindIII (both purchased from TaKaRa Company), and the amplified fragment of the luxS gene was recovered by gel recovery. Figure 1 C, then the recovered luxS gene fragment was connected with the plasmid fragment pMG36e treated with XbaI and HindIII double enzymes to obtain a connection product. The connection product was transformed into E. coli DH5α competent cells and evenly spread on LB plates with erythromycin resistance (600μg / mL), cultured at 37℃ overnight, and a single clone was picked for colony PCR verification and enzyme digestion verification. The sequencing was correct, such as Figure 1 As shown in D, the vector pMG36e containing the luxS gene, namely pMG36e-luxS, was obtained.

[0032] The LB medium is: trypsin: 10.0 g / L, yeast extract: 5.0 g / L, NaCl: 10.0 g / L, dissolved in deionized water, fixed to 1.0 L, pH adjusted to 7.0-7.2, 1.5% agar powder added to the solid medium, sterilized at 121°C for 20 min.

[0033] 2. Construction of luxS gene overexpression strain.

[0034] Prepare competent cells as follows:

[0035] 1. Inoculate 2% of L. plantarum HRB1 into 10 mL of MRS medium and culture at 37°C for 16 h;

[0036] 2. Take 1 mL of the cultured strain and inoculate it into 100 mL of MRS medium containing 2.5% glycine. After culturing for 3-4 hours, measure its OD 600 When the value reaches 0.5-0.6, the culture is stopped and the bacteria are collected by centrifugation at 12000 rpm / min for 10 min at 4°C;

[0037] 3. Add 25 mL of sterilized water to wash the cells twice. After centrifugation, discard the supernatant. Note that the whole process should be operated at low temperature.

[0038] 4. Resuspend the washed cells in 0.05 mol / L EDTA solution, place on ice for 5 min, add 25 mL of pre-cooled sterile water, centrifuge at 4°C, 12000 rpm / min for 10 min, and wash again with 25 mL of pre-cooled sterile water;

[0039] 5. Use 25 mL of pre-cooled electroporation buffer, centrifuge at 4°C, 12,000 rpm / min for 10 min, and repeat step 4 once;

[0040] 6. Resuspend the washed bacteria in 0.8 mL of electroporation buffer and dispense 100 μL of the aliquots into sterilized 1.5 mL centrifuge tubes. Make sure to operate on ice during aliquoting to obtain competent cells, which are then stored at -80°C for later use.

[0041] Electrotransformation of Lactobacillus plantarum was performed as follows:

[0042] 1. Thaw 100 μL of competent cells on ice, add 10 μL of pMG36e-luxS vector DNA, gently pipette and mix, and place on ice for 5 min to obtain a pMG36e-luxS mixture; Thaw 100 μL of competent cells on ice, add 10 μL of pMG36e vector DNA, gently pipette and mix, and place on ice for 5 min to obtain a pMG36e mixture;

[0043] 2. Transfer the two mixtures (110 μL) into pre-cooled electroporation cups with a spacing of 1 mm, and immediately place them in an electroporator at a voltage of 1.25 kV. If the spacing of the electroporation cups is 2 mm, use a voltage of 2.5 kV for electroporation.

[0044] 3. After the electroporation is completed, quickly add 890 μL of fresh MRS culture medium to the electroporation cup, gently blow and mix with the pipette tip, and then transfer the mixture to a sterile 2 mL centrifuge tube. Incubate at 28°C for 2.5 hours to allow the cells to recover.

[0045] 4. After culture, centrifuge the bacterial solution at 8000 rpm / min for 3 min, discard 900 μL of supernatant, resuspend the bacteria in the remaining 100 μL of supernatant, spread on a MRS-resistant plate containing 100 μg / mL erythromycin, and culture at 28°C.

[0046] 5. Pick a single colony and culture it in MRS culture medium containing erythromycin to obtain the strain L. plantarum HRB1 pMG36e containing an empty plasmid and the strain L. plantarum HRB1 pMG36e-luxS overexpressing the luxS gene. Perform PCR verification on the bacterial solution. The verification results are as follows: Figure 1As shown in E, the correct strains L. plantarum HRB1pMG36e and strain L. plantarum HRB1pMG36e-luxS were obtained.

[0047] Example 2. Determination of the production of quorum sensing signal molecule AI-2

[0048] 1. Determination of the production of quorum sensing signal molecule AI-2:

[0049] V. harveyi BB170 (purchased from Shanghai Collection Biotechnology Center, number SHBCC D24812) was inoculated into AB medium (17.5 g sodium chloride, 12.3 g magnesium sulfate and 2.0 g acid hydrolyzed casein per liter) at 2% and cultured at 30°C, 120 r / min, with shaking until the second generation. OD 600 nm value between 0.7-1.2, dilute the V. harveyi BB170 culture medium at 1:5000 (v / v) with fresh AB medium, mix well and set aside.

[0050] Three lactic acid bacteria strains, L. plantarum HRB1, L. plantarum HRB1 pMG36e and L. plantarum HRB1pMG36e-luxS, were inoculated into MRS medium and activated for three generations before preparing lactic acid bacteria culture fluid. L. plantarumHRB1 lactic acid bacteria culture fluid, L. plantarum HRB1pMG36e lactic acid bacteria culture fluid, L. plantarum HRB1pMG36e-luxS lactic acid bacteria culture fluid, V. harveyi BB170 culture fluid, AB culture medium and MRS liquid culture medium were centrifuged at 8000r / min (4°C) for 5 min, the bacterial sludge was discarded, and the supernatant was filtered through a 0.22μm sterile membrane to remove impurities, thereby obtaining the test samples (L. plantarumHRB1 lactic acid bacteria culture fluid, L. plantarum HRB1pMG36e-luxS lactic acid bacteria culture fluid and L. plantarum HRB1pMG36e lactic acid bacteria culture fluid), positive control (sterile supernatant of V. harveyi BB170 culture fluid), negative control (sterile supernatant of AB culture medium) and medium control (sterile supernatant of MRS liquid culture medium). The sample to be tested, positive, negative, and medium controls were mixed with the diluted V. harveyi BB170 bacterial solution at a ratio of 1:100 (v / v) and continued to be shaken and cultured. The fluorescence intensity value was measured every 4 hours within 0-24 hours. The relative fluorescence intensity was calculated to represent the activity of the signal molecule AI-2.

[0051] Relative fluorescence intensity calculation formula:

[0052] Formula (1): Relative fluorescence intensity of the Vibrio positive control group = fluorescence intensity value of the positive control / fluorescence intensity value of the negative control;

[0053] Formula (2): Relative fluorescence intensity of lactic acid bacteria = fluorescence intensity value of the sample to be tested / fluorescence intensity value of the medium control.

[0054] The results are as follows Figure 2 As shown, when the culture time exceeded 4 h, the ability of L. plantarum HRB1 pMG36e-luxS to produce the signal molecule AI-2 was significantly higher than that of L. plantarum HRB1 and L. plantarum HRB1pMG36e, and there was no significant difference in the ability of L. plantarumHRB1 and L. plantarum HRB1 pMG36e to produce the signal molecule AI-2.

[0055] 2. Determination of protease activity in culture medium:

[0056] A full inoculation loop of L. plantarum HRB1, L. plantarum HRB1pMG36e and L. plantarum HRB1 pMG36e-luxS was scraped from the culture medium and inoculated into a 250 mL conical flask of MRS medium and cultured at 37°C in a shaker at 200 rpm for 24 h. Protease activity was measured every 4 h.

[0057] The protease activity is mainly measured by the ability to hydrolyze azocasein. The specific steps are as follows: Take 10 mL of culture medium, break the cells on an ultrasonic disruptor under ice bath, turn on for 3s, turn off for 3s, and alternately break the cycle for a total of 15 minutes. The broken cells are centrifuged at 4°C, 13000r / min for 10 minutes, and at 4°C, 10000rpm for 10 minutes. 0.5 mL of cell-free supernatant is taken and mixed with 0.5 mL of 0.1 mol Tris-HCl buffer (pH 8.0) containing 0.8% (w / v) azocasein. The reaction mixture is placed in a water bath at 40°C for 2 hours, 1 mL of 10% (w / v) trichloroacetic acid is added to terminate the reaction, and then the mixture is placed on ice for 30 minutes. The precipitate is removed by centrifugation at 4°C, 10000rpm for 10 minutes. Transfer 600 μL of the reaction supernatant to a new ep tube and add 700 μL of 1 mol / L NaOH, and measure the absorbance at 440 nm using an ELISA reader. The protease activity value is calculated as follows:

[0058]

[0059] A: Absorbance of crude enzyme solution; B: Absorbance of control group

[0060] The protease activity unit (U) is defined as the enzyme activity that changes the absorbance by 0.01 at 440 nm within 2 hours at 40°C under standard assay conditions. 2 is the total reaction volume, 0.5 is the volume of the crude enzyme solution

[0061] Results: From Figure 3 It can be seen that the protease activity of L. plantarum HRB1 pMG36e-luxS was significantly higher than that of the other two lactic acid bacteria (P<0.05).

[0062] 3. Determination of lipase activity in culture medium:

[0063] A full inoculation loop of L. plantarum HRB1, L. plantarum HRB1pMG36e and L. plantarum HRB1 pMG36e-luxS was scraped from the culture medium and inoculated into a 250 mL conical flask of MRS medium and cultured at 37°C in a shaker at 200 rpm for 24 h. Lipase activity was measured every 4 h.

[0064] The specific steps are as follows: Take 10mL of culture medium, break the cells on an ultrasonic disruptor under ice bath, turn on for 3s, turn off for 3s, and alternately break the cycle for a total of 15min. Centrifuge the broken cells at 4℃, 13000r / min for 10min, and at 4℃, 10000rpm for 10min to obtain crude enzyme solution. The lipase activity determination mainly uses p-nitrophenol palmitate (p-NPP) as the reaction substrate. Take 600μL 2.0Mm p-nitrophenol, add 25μL crude enzyme solution and react at 40℃ for 15min. After the reaction is completed, add 500μL 95% ethanol to terminate the reaction. For the control group, add 25μL pH 7.0 Tris-HCl buffer, keep it at 40℃ for 15min, and then add 500μL 95% ethanol. After mixing, centrifuge at 10000rpm4℃ for 3min, and then measure the absorbance at 410nm. One unit of enzyme activity (U) represents the amount of enzyme that produces 1 μM p-nitrophenol (pNP) by catalyzing the hydrolysis of the substrate p-nitrophenol palmitate (pNPP) within 1 min.

[0065] from Figure 4 It can be seen that the lipase activity of L. plantarum HRB1 pMG36e-luxS was significantly higher than that of the other two lactic acid bacteria (P<0.05).

[0066] Example 3. Preparation of microbial preparation of Lactobacillus plantarum

[0067] 1. Activation of Lactobacillus plantarum:

[0068] Take 100-300 μL of L. plantarum HRB1 pMG36e-luxS in the glycerol tube and inoculate it into 500-1000 mL of MRS broth medium. Incubate at 37°C for 24-48 hours. Repeat this step 2-4 times to obtain activated Lactobacillus plantarum culture. Centrifuge the activated culture, discard the supernatant, wash with sterile saline and resuspend, centrifuge and discard the supernatant. Repeat this step 2-3 times to obtain a cell concentration of 10 6 -10 7 CFU / g of active bacterial sludge.

[0069] 2. Preparation of bacterial powder biological preparations:

[0070] Skim milk was selected as a freeze-drying protective agent, and the bacterial sludge obtained in the previous step and the skim milk were mixed at a mass ratio of 1:10 to obtain a bacterial cell concentration of 10 5 -10 6 CFU / mL skim milk suspension of plant lactobacillus HRB1pMG36e-luxS was pre-cultured at 37°C for 2 hours and then pre-frozen in a -40°C refrigerator for about 5-7 hours. After pre-freezing, it was freeze-dried in a vacuum freeze dryer. 5 -10 7 CFU / g of freeze-dried Lactobacillus plantarum HRB1 pMG36e-luxS biological preparation.

[0071] Example 4. Application of Lactobacillus plantarum HRB1 pMG36e-luxs

[0072] 1. Production of air-dried sausage

[0073] (1) Preparation of air-dried sausage

[0074] Ingredients: 9.0kg lean meat (pork tenderloin), 1.0kg fat (pork back fat), 0.30kg koji wine, 0.20kg salt, 0.0090kg sodium nitrite, 0.5kg granulated sugar, 0.15kg MSG, 0.05kg mixed seasoning (Shiyitang dry sausage material).

[0075] (2) Preparation of starter culture

[0076] The biological preparations Lactobacillus plantarum HRB1 and L. plantarum HRB1pMG36e-luxS were subcultured twice in MRS medium and cultured at 37°C for 18 hours. After centrifugation at 4°C and 10,000×g for 5 minutes, they were set aside. When adding the starter, the amount of lactic acid bacteria added was 10 6 CFU / g minced meat.

[0077] Process flow: Raw meat (remove connective tissue such as lymph, tendons, and blood vessels) → dice (1cm 3 diced meat) → marinate (add salt and seasoning, etc.) → add leavening agent → mix stuffing → stuffing (length 20cm, diameter 3cm) → ferment and air-dry (temperature 25±2℃, humidity 65±5%).

[0078] 2. Determination of free amino acids

[0079] Air-dried sausage samples (10.0 g) were homogenized in 0.1 mol / L HCl 1:5 (w / v) for 30 min, then centrifuged at 10000 rpm for 20 min at 0 °C, and the supernatant was filtered through a 0.45 μm filter membrane. Then, 1.0 mL of the liquid was transferred to a glass tube and derivatized using phenyl isothiocyanate (PITC) reagent. Amino acids were analyzed using a high-performance liquid chromatography system equipped with an Accucore C18 column (3×150 mm, 2.6 μm) with a detection wavelength of 254 nm and a flow rate of 1 mL / min. Each amino acid in the air-dried sausage was qualitatively and quantitatively determined by comparing the retention time and peak area of ​​each amino acid standard. The content of free amino acids was expressed in mg / g dry matter, and the results are shown in Table 2. As can be seen from Table 2, for the free amino acid content in sausages, the glutamic acid, serine, proline, lysine, etc. of the air-dried sausage of the LP-L group were significantly higher than those of the air-dried sausage of the C and LP groups. In addition, the total free amino acid content of the LP-L group was significantly higher than that of the C and LP groups.

[0080] Table 2 Free amino acid content in dry sausages inoculated with different lactic acid bacteria strains at the end of fermentation

[0081]

[0082]

[0083] Note: Different lowercase letters in the same row indicate significant differences among different treatments (P<0.05).

[0084] nd: Not detected

[0085] C: control group; LP: treatment group inoculated with L. plantarum HRB1; LP-L: treatment group inoculated with L. plantarum HRB1pMG36e-luxS

[0086] 3. Content of Volatile Compounds

[0087] The volatile compounds in the air-dried intestines were extracted by headspace solid phase microextraction. The chopped air-dried intestines (3.0 g) were placed in a 20 mL headspace sample bottle, and 4 μL of o-dichlorobenzene was added as an internal standard. The headspace adsorption was performed with a 50 / 30 μm DVB / CAR / PDMS extraction head at 45 °C for 30 min, and then the extraction head was immediately inserted into the gas injection port for 3 min of analysis.

[0088] The volatile compounds were determined using a gas chromatography-mass spectrometry (GC-MS) system (QP2020, Shimadzu). The gas chromatography conditions were: InertCap WaX capillary column (60m×0.25mm×0.25μm); injection port temperature was 230℃; injection was performed in splitless mode; helium was used as the carrier with a flow rate of 1mL / min; programmed temperature: column initial temperature was 40℃, maintained for 3min, increased to 200℃ at 5℃ / min, and then increased to 230℃ at 10℃ / min, and maintained for 2min. Mass spectrometry conditions: ion source temperature was 230℃; mass scanning range was 45-500 (m / z).

[0089] The identification of volatile compounds was performed by comparing with the NIST 17 mass spectral library, taking the similarity greater than 90% as the identification result, and calculating the standard alkane (C 6 -C 20 ) retention index (LRI) was compared with the results reported in the literature for auxiliary identification. The volatile compounds were quantified by the internal standard method, with o-dichlorobenzene solution dissolved in n-hexane as the internal standard substance. The quantitative results were expressed in μg / kg, and the results are shown in Table 3. As can be seen from Table 3, compared with the other two groups of sausages, the inoculation of L. plantarum HRB1pMG36e-luxS can significantly enhance the content of aldehydes, ketones, alcohols, acids, esters and terpenes in the fermented sausages, and significantly promote the formation of product flavor.

[0090] Table 3 Content of volatile flavor substances in dry sausages inoculated with different lactic acid bacteria strains at the end of fermentation

[0091]

[0092]

[0093]

[0094] Note: Different lowercase letters in the same row indicate significant differences among different treatments (P<0.05).

[0095] nd: Not detected

[0096] LRI: Linear Retention Index

[0097] C: control group; LP: treatment group inoculated with L. plantarum HRB1; LP-L: treatment group inoculated with L. plantarum HRB1pMG36e-luxS.

Claims

1. A Lactobacillus plantarum, characterized in that The plant lactobacillus is L. plantarum HRB1pMG36e-luxS.

2. The plant lactobacillus according to claim 1, characterized in that The plant lactobacillus is obtained by transforming plasmid pMG36e-luxS into L. plantarum HRB1.

3. Use of L. plantarum HRB1 pMG36e-luxS according to claim 1 in preparing air-dried sausage.

4. A microbial preparation of Lactobacillus plantarum, characterized in that The microbial preparation is prepared using the L. plantarum HRB1 pMG36e-luxS described in claim 1.

5. A method for preparing a Lactobacillus plantarum microbial preparation, characterized in that: The preparation method comprises the following steps: activating L. plantarum HRB1 pMG36e-luxS, discarding the supernatant by centrifugation to obtain active bacterial sludge, mixing the active bacterial sludge with skim emulsion and then culturing the mixture, pre-freezing the cultured active bacterial sludge and the skim emulsion, and placing the mixture in a vacuum freeze dryer for freeze drying after the pre-freezing is completed.

6. The preparation method according to claim 5, characterized in that: The concentration of bacteria in the active bacterial sludge is 10 6 -10 7 CFU / g.

7. The preparation method according to claim 5, characterized in that: The active bacterial mud and the skimmed emulsion are mixed at a mass ratio of 1:

10.

8. The preparation method according to claim 5, characterized in that: The active bacterial sludge and the skimmed emulsion are mixed and cultured at 37° C. for 2 hours.

9. The preparation method according to claim 5, characterized in that: The pre-freezing is pre-freezing in a -40°C refrigerator for 5-7h.

10. Use of the microbial preparation according to claim 4 in the preparation of air-dried sausage.

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