A method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by quorum sensing

Abstract

The present invention belongs to the field of microbial fermentation engineering, and discloses a method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing. The method is to inoculate Saccharomyces cerevisiae GIM2.188 into the YPD medium containing 2-phenylethanol at an inoculum size of (1-4)×10 5 cells / mL, and ferment and culture for 9-12 h; or inoculate Saccharomyces cerevisiae and Lactobacillus plantarum into the YPD medium containing 2-phenylethanol at an inoculum size of (1-4)×10 5 cells / mL and 1×(10 6 -10 8 ) cells / mL respectively, the concentration of the 2-phenylethanol is 30-120 mg / L, and ferment and culture for 9-30 h, so as to simultaneously increase ethanol production and reduce the harm of bacterial contamination. The method of the present invention is simple to operate, low in cost, has no influence on the growth of Saccharomyces cerevisiae, and has good application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of microbial fermentation engineering, and more specifically, relates to a method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing. Background Art

[0002] With the continuous depletion of traditional fossil energy, the development and utilization of new energy are imminent. As a renewable green energy, bioethanol can replace some fossil fuels, which is of great significance for alleviating energy pressure and improving environmental quality, and thus has received extensive attention from governments and academia around the world.

[0003] Currently, 95% of fuel ethanol is produced by microbial fermentation, and bioethanol has become the largest-scale fermentation product in the world. However, with the development of society and the growth of population, the demand for ethanol production has increased sharply. The first-generation bioethanol using food crops as raw materials can no longer meet the current demand for ethanol, and the second-generation bioethanol using non-food crops such as lignocellulose still needs to be strengthened in terms of fermentation efficiency and process. In the industrial bioethanol fermentation production process, it is often affected by bacterial contamination. Among them, lactic acid bacteria are considered to be the main contaminating bacteria in the industrial bioethanol fermentation process. Lactic acid bacteria inhibit the ethanol fermentation process by competing with Saccharomyces cerevisiae for nutrients, secreting acidic substances to lower the pH of the fermentation system, and competing for living space. Therefore, finding a method that can both promote ethanol production by Saccharomyces cerevisiae and reduce the impact of bacterial contamination is of great significance for the development of industrial bioethanol.

[0004] Quorum sensing is a communication mechanism between microorganisms. During the growth of microorganisms, quorum sensing signal molecules are secreted into the environment. When the concentration of the signal molecules reaches a certain threshold, they are detected by the microorganisms and regulate the expression of related genes, such as bacterial luminescence, biofilm formation, production of virulence factors and antibiotics. 2-Phenylethanol has been confirmed as one of the signal molecules of Saccharomyces cerevisiae and can promote the pseudohyphal growth of Saccharomyces cerevisiae under nitrogen-poor conditions. However, the research on the impact of 2-phenylethanol on the bioethanol fermentation system has not been reported. Summary of the Invention

[0005] The object of the present invention is to provide a method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing in view of the above problems. This method is to culture Saccharomyces cerevisiae alone or co-culture Saccharomyces cerevisiae GIM2.188 with Lactobacillus plantarum ATCC8014 to simulate the problem of bacterial contamination in the industrial bioethanol fermentation process. By adding the quorum sensing signal molecule 2-phenylethanol of Saccharomyces cerevisiae to the culture medium, it can effectively promote the ethanol production during the fermentation process of Saccharomyces cerevisiae, enhance the ability of Saccharomyces cerevisiae to produce ethanol, and reduce the impact of Lactobacillus plantarum on ethanol production.

[0006] The object of the present invention is achieved by the following technical solutions:

[0007] A method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing. In this method, Saccharomyces cerevisiae GIM2.188 (preservation number: GDMCC 2.188) is inoculated into YPD medium containing 2-phenylethanol at an inoculum size of (1-4)×10 5 cells / mL, and fermented and cultured at 28 °C and 180 rmp / min for 9-12 h; or Saccharomyces cerevisiae and Lactobacillus plantarum are respectively inoculated into YPD medium containing 2-phenylethanol at inoculum sizes of (1-4)×10 5 cells / mL and 1×10 6 -1×10 8 cells / mL. The concentration of 2-phenylethanol is 30-120 mg / L, and it is fermented and cultured at 28 °C and 180 rmp / min for 9-30 h to promote Saccharomyces cerevisiae to produce ethanol and reduce the harm of bacterial contamination.

[0008] Preferably, the inoculum size of the Saccharomyces cerevisiae is to inoculate Saccharomyces cerevisiae GIM2.188 into YPD medium, culture it at 28 °C and 180 rmp / min for 9-12 h for activation, then inoculate the activated strain into YPD medium again and culture it for 9-12 h, and determine it as (1-4)×10 5 cells / mL by using a hemocytometer.

[0009] Preferably, the inoculum size of the Lactobacillus plantarum is to inoculate Lactobacillus plantarum ATCC8014 into MRS medium, statically culture it in a 37 °C constant temperature incubator for 9-12 h for activation, then inoculate the activated strain into MRS medium again and culture it for 9-12 h, and determine it as 1×10 6 -1×10 8 cells / mL by the dilution coating method.

[0010] In the method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing, the bacteria in the bacterial contamination harm are Lactobacillus.

[0011] Preferably, the Lactobacillus genus is Lactobacillus plantarum ATCC8014 (deposit number: GDMCC 1.140), Lactobacillus plantarum ACCC 11095 (deposit number: GDMCC 1.191), Lactobacillus acidophilus (deposit number: GDMCC 1.731), Lactobacillus brevis (deposit number: GDMCC 1.773), Lactobacillus plantarum (deposit number: GDMCC 1.2868), Lactobacillus casei (deposit number: GDMCC 1.2885), Lactobacillus acidophilus (deposit number: GDMCC 1.1807). The present invention is not limited thereto. Other bacteria belonging to the Lactobacillus genus and being the main contaminating bacteria during the bioethanol fermentation process can all use the present invention to reduce their impact on ethanol production.

[0012] Compared with the existing technology, the present invention has the following beneficial effects:

[0013] 1. The present invention cultures Saccharomyces cerevisiae alone or co-cultures Saccharomyces cerevisiae GIM2.188 with Lactobacillus plantarum (such as Lactobacillus plantarum ATCC8014). By adding 2-phenylethanol to the YPD medium, it can effectively promote the ethanol production during the fermentation process of Saccharomyces cerevisiae, and the concentration of exogenously added 2-phenylethanol is at the concentration level that Saccharomyces cerevisiae can produce by itself. Therefore, it will not affect the growth of yeast cells.

[0014] 2. After the present invention cultures Saccharomyces cerevisiae alone or co-cultures Saccharomyces cerevisiae GIM2.188 with Lactobacillus plantarum (such as Lactobacillus plantarum ATCC8014), adding 2-phenylethanol can reduce the impact of Lactobacillus plantarum contamination on ethanol production, which has important application value for reducing the harm caused by Lactobacillus plantarum contamination during the bioethanol fermentation process. Description of the Drawings

[0015] Figure 1 It is the concentration curve of 2-phenylethanol and the growth curve during the fermentation process of Saccharomyces cerevisiae in Example 1;

[0016] Figure 2 It is the effect of adding different concentrations of 2-phenylethanol on the ethanol production of Saccharomyces cerevisiae in Example 2;

[0017] Figure 3 It is the change curve of ethanol concentration produced by the co-fermentation of Saccharomyces cerevisiae and Lactobacillus plantarum with the addition of 120 mg / L of 2-phenylethanol in Example 3. Detailed Embodiments

[0018] The content of the present invention will be further described below in conjunction with specific embodiments, but it should not be construed as a limitation to the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well-known to those skilled in the art. Unless otherwise specified, the methods and equipment adopted in the present invention are conventional methods and equipment in the technical field.

[0019] The Saccharomyces cerevisiae GIM2.188 (preservation number: GDMCC 2.188) and Lactobacillus plantarum ATCC8014 (preservation number: GDMCC 1.140) used in the present invention are both purchased from the Guangdong Provincial Culture Collection Center of Microorganisms.

[0020] Example 1

[0021] 1. The concentration of 2-phenylethanol produced by Saccharomyces cerevisiae during fermentation, the specific steps are as follows:

[0022] (1) Preparation of the medium: Prepare 640 mL of liquid YPD medium (20 g of glucose, 20 g of peptone, 10 g of yeast extract, prepared with 1 L of deionized water, and 2% agar powder is added to the slant medium), dispense 180 mL into 3 250 mL conical flasks, and divide the remaining 100 mL of liquid YPD medium equally into 2 250 mL conical flasks as the activation medium and calculate the inoculation amount. All media are sterilized at 115 °C for 20 min.

[0023] (2) Activation of Saccharomyces cerevisiae and determination of the inoculation amount: Inoculate two loops of Saccharomyces cerevisiae GIM2.188 from the slant medium into 50 mL of YPD medium, culture and activate it at 28 °C and 180 rmp / min for 9 - 12 h. Transfer 1 mL of the activated bacterial liquid to 50 mL of YPD medium and culture it again for 9 - 12 h. Transfer 1 mL of the cultured bacterial liquid and dilute it 20 times with sterile water. Use a dropper to suck a little of the diluted bacterial liquid and drop it onto a hemocytometer covered with a cover glass, and count the specified field of view under a microscope. Determine the inoculation amount of Saccharomyces cerevisiae according to 1×10 5 cells / mL - 4×10 5 cells / mL.

[0024] (3) Cultivation of Saccharomyces cerevisiae: Inoculate Saccharomyces cerevisiae into 180 mL of YPD medium for cultivation according to the inoculation amount determined in step (2), and culture it at 28 °C and 180 rmp / min for 144 h. Take samples every 36 h, centrifuge at 8000 rpm / min for 10 min, and filter the supernatant through a 0.22 um organic phase filter head for the determination of the concentration of 2-phenylethanol.

[0025] 2.2 - Determination of 2 - phenylethanol: An ultra - performance liquid chromatography - tandem mass spectrometry was used to quantify the concentration of 2 - phenylethanol during the fermentation of Saccharomyces cerevisiae (refer to Growth Regulation in Amphibian Pathogenic Chytrid Fungiby the Quorum Sensing Metabolite Tryptophol). Figure 1 It is the concentration of 2 - phenylethanol and the growth curve during the fermentation of Saccharomyces cerevisiae in Example 1. As Figure 1 shown, when Saccharomyces cerevisiae was fermented for 144 h, the concentration of 2 - phenylethanol gradually became stable at 118.02 mg / L.

[0026] Example 2

[0027] The influence of the concentration of 2 - phenylethanol on the ethanol production of the single - fermentation system of Saccharomyces cerevisiae is as follows:

[0028] (1) Preparation of the medium: Prepare 2260 mL of liquid YPD medium for the single - fermentation system of Saccharomyces cerevisiae, and dispense 180 mL into 12 250 - mL conical flasks. Add 2 - phenylethanol to 9 of them so that the final concentrations are 30 mg / L, 60 mg / L, and 120 mg / L respectively, with three parallels for each concentration. Add an equal volume of distilled water to the other 3 flasks as a control group. Divide the remaining 100 mL of liquid YPD medium equally into 2 250 - mL conical flasks as the activation medium and calculate the inoculation amount.

[0029] (2) Activation of Saccharomyces cerevisiae and determination of the inoculation amount: Inoculate two loops of Saccharomyces cerevisiae GIM2.188 from the slant medium into 50 mL of YPD medium, and culture and activate it at 28 °C and 180 rmp / min for 9 - 12 h. Transfer 1 mL of the activated bacterial liquid to 50 mL of YPD medium and culture it again for 9 - 12 h. Transfer 1 mL of the cultured bacterial liquid and dilute it 20 times with sterile water. Use a dropper to suck a little of the diluted bacterial liquid and drop it onto a hemocytometer covered with a coverslip, and count the specified fields of view under a microscope. Determine the inoculation amount of Saccharomyces cerevisiae according to 1×10 5 cells / mL~4×10 5 cells / mL.

[0030] (3) According to the inoculation amount determined in step (2), inoculate Saccharomyces cerevisiae into the YPD medium added with different concentrations of 2-phenylethanol in step (1) and the YPD medium with an equal amount of distilled water as the control group, and culture at 28 °C and 180 rmp / min for 9 - 30 h, then sample to measure the ethanol concentration. Table 1 shows the effects of different concentrations of 2-phenylethanol on the ethanol production in the single fermentation system of Saccharomyces cerevisiae. As can be seen from Table 1, at 9 h of fermentation, with the increase in the concentration of 2-phenylethanol, the ethanol concentration gradually increases, which is 59%, 55%, and 45% higher than that of the control group respectively (P < 0.05). At 12 h of fermentation, only the treatment group added with 120 mg / L 2-phenylethanol has a significant difference in ethanol production compared with the control group, with a 9% increase (P < 0.05). At 24 - 30 h of fermentation, the glucose in the system has been consumed, and at this time, 2-phenylethanol does not show a promoting effect on ethanol fermentation.

[0031] Table 1 Effects of different concentrations of 2-phenylethanol on the ethanol production in the single fermentation system of Saccharomyces cerevisiae

[0032]

[0033] Figure 2 It is the effects of adding different concentrations of 2-phenylethanol on the ethanol production of Saccharomyces cerevisiae in Example 2; as can be seen from Figure 2 it, the ethanol production has increased after adding 2-phenylethanol, and the addition of 120 mg / L 2-phenylethanol has the most obvious improvement effect.

[0034] Example 3

[0035] Effects of the concentration of 2-phenylethanol on the ethanol production in the co-fermentation system of Saccharomyces cerevisiae and Lactobacillus plantarum are as follows:

[0036] (1) Preparation of culture media: Prepare 2260 mL of liquid YPD medium for the co-fermentation system of Saccharomyces cerevisiae and Lactobacillus plantarum. Dispense 180 mL into 12 250-mL conical flasks. Add 2-phenylethanol to 9 of them to make the final concentrations 30 mg / L, 60 mg / L, and 120 mg / L respectively, with three parallels for each concentration. Add an equal amount of distilled water to the other 3 flasks as the contaminated group. Divide the remaining 100 mL of liquid YPD medium equally into 2 250-mL conical flasks as the activation medium and calculate the inoculation amount. Prepare 300 mL of liquid MRS medium (20 g of glucose, 10 g of beef extract, 10 g of peptone, 5 g of yeast extract, 5 g of sodium acetate, 2 g of diammonium citrate, 2 g of dipotassium hydrogen phosphate, 0.58 g of magnesium sulfate heptahydrate, 0.25 g of manganese sulfate monohydrate, 1 mL of Tween-80, prepared with 1 L of deionized water, and add 2% agar powder to the slant medium). Divide 100 mL equally into 2 250-mL conical flasks as the activation medium and calculate the inoculation amount. Add 2 g of agar powder to the remaining 200 mL of liquid MRS medium to make a solid medium. Sterilize all the media at 115 °C for 20 min.

[0037] (2) Activation of Saccharomyces cerevisiae and determination of inoculation amount: Inoculate two loops of Saccharomyces cerevisiae GIM2.188 from the slant medium into 50 mL of YPD medium, and culture and activate it at 28 °C and 180 rmp / min for 9 - 12 h. Transfer 1 mL of the activated bacterial liquid to 50 mL of YPD medium and culture it again for 9 - 12 h. Transfer 1 mL of the cultured bacterial liquid and dilute it 20 times with sterile water. Use a dropper to suck a little of the diluted bacterial liquid and drop it onto a hemocytometer covered with a coverslip, and count the specified fields of view under a microscope. Determine the inoculation amount of Saccharomyces cerevisiae according to 1×10 5 cells / mL - 4×10 5 cells / mL.

[0038] (3) Activation of Lactobacillus plantarum and determination of inoculation amount: Inoculate five loops of Lactobacillus plantarum ATCC8014 from the slant medium into 50 mL of MRS medium, and culture it statically at 37 °C for 9 - 12 h. Transfer 10 mL of the activated bacterial liquid to 50 mL of MRS medium and culture it again for 9 - 12 h. Dilute the cultured bacterial liquid by 10 7 times in three portions. Use a pipette to transfer 100 μL of the diluted liquid to 3 sterilized petri dishes respectively, gently pour 50 °C MRS solid medium into them and shake well. After the medium solidifies, place it in an incubator at 37 °C and culture for 24 h. Determine the inoculation amount of Lactobacillus plantarum according to 1×10 8 cells / mL.

[0039] (4) According to the inoculation amounts determined in steps (2) and (3), simultaneously inoculate Saccharomyces cerevisiae and Lactobacillus plantarum into the YPD medium with different concentrations of 2-phenylethanol added in step (1) and the YPD medium with an equal amount of distilled water as the contaminated group, and culture at 28 °C and 180 rmp / min for 9 - 30 h, then sample to measure the ethanol concentration. Table 2 shows the effects of different concentrations of 2-phenylethanol on the ethanol production of the co-fermentation system of Saccharomyces cerevisiae and Lactobacillus plantarum. Comparing the control group and the contaminated group in Table 1 and Table 2, it can be seen that the contamination of Lactobacillus plantarum reduces the ethanol production of Saccharomyces cerevisiae; when fermented for 12 - 30 h, compared with the control group, the ethanol production of the contaminated group is reduced by 5.1 - 37.7%. However, the addition of 2-phenylethanol promotes the ethanol production of Saccharomyces cerevisiae and reduces the impact brought by the contamination of Lactobacillus plantarum. When fermented for 9 h, the treatment group with 2-phenylethanol added is 4.3 - 18.5% higher than the contaminated group, and when fermented for 12 h, the treatment group with 2-phenylethanol added is 5.9 - 14.3% higher than the contaminated group.

[0040] Table 2 Effects of different concentrations of 2-phenylethanol on the ethanol production of the co-fermentation system of Saccharomyces cerevisiae and Lactobacillus plantarum

[0041]

[0042] Figure 3 is the change curve of ethanol concentration produced by the co-fermentation of Saccharomyces cerevisiae and Lactobacillus plantarum with the addition of 120 mg / L of 2-phenylethanol in Example 3; as can be seen from Figure 3 it, adding 120 mg / L of 2-phenylethanol to the fermentation system of Saccharomyces cerevisiae contaminated by Lactobacillus plantarum can still increase the ethanol production. During the logarithmic phase of rapid growth of Lactobacillus plantarum (fermented for 12 h), the ethanol concentration of the treatment group with 120 mg / L of 2-phenylethanol added can even recover to a level comparable to that of Saccharomyces cerevisiae fermented alone, which is 14.3% higher than the contaminated group.

[0043] Example 4

[0044] Effects of adding 2-phenylethanol on the ethanol production of Saccharomyces cerevisiae under different inoculation amounts of Lactobacillus plantarum.

[0045] (1) Preparation of culture media: Prepare 3340 mL of liquid YPD medium, and dispense 180 mL into 18 250-mL conical flasks. Add 2-phenylethanol to 9 of these flasks to a final concentration of 120 mg / L, and add an equal volume of distilled water to the other 9 flasks as the contaminated group. Divide the remaining 100 mL of liquid YPD medium equally into 2 250-mL conical flasks as the activation medium and calculate the inoculum amount. Prepare 300 mL of liquid MRS medium, divide 100 mL equally into 2 250-mL conical flasks as the activation medium and calculate the inoculum amount. Add 2 g of agar powder to the remaining 200 mL of liquid MRS medium to make a solid medium. Sterilize all the media at 115 °C for 20 min.

[0046] (2) Activation of Saccharomyces cerevisiae and determination of inoculum amount: Inoculate two loops of Saccharomyces cerevisiae GIM2.188 from the slant medium into 50 mL of YPD medium, and culture and activate it at 28 °C and 180 rmp / min for 9 - 12 h. Transfer 1 mL of the activated bacterial solution to 50 mL of YPD medium and culture it again for 9 - 12 h. Transfer 1 mL of the cultured bacterial solution and dilute it 20 times with sterile water. Use a dropper to suck a little of the diluted bacterial solution and drop it onto a hemocytometer covered with a coverslip, and count the cells in the specified field of view under a microscope. Determine the inoculum amount of Saccharomyces cerevisiae according to 1×10 5 cells / mL - 4×10 5 cells / mL.

[0047] (3) Activation of Lactobacillus plantarum and determination of inoculum amount: Inoculate five loops of Lactobacillus plantarum ATCC8014 from the slant medium into 50 mL of MRS medium, and culture it statically at 37 °C for 9 - 12 h. Transfer 10 mL of the activated bacterial solution to 50 mL of MRS medium and culture it again for 9 - 12 h. Dilute the cultured bacterial solution by 10 7 in three portions. Use a pipette to transfer 100 μL of the diluted solution to three sterilized petri dishes respectively, gently pour 50 °C MRS solid medium into them and shake well. After the medium solidifies, incubate it at 37 °C under constant temperature for 24 h. Determine the inoculum amount of Lactobacillus plantarum according to 1×10 6 cells / mL, 1×10 7 cells / mL, 1×10 8 cells / mL respectively.

[0048] (4) According to the inoculation amounts determined in steps (2)-(3), simultaneously inoculate Saccharomyces cerevisiae and Lactobacillus plantarum into the YPD medium supplemented with 120 mg / L 2-phenylethanol in step (1) and the YPD medium with an equal amount of distilled water as the contaminated group, and culture at 28 °C and 180 rmp / min for 12 h, then take samples to measure the ethanol concentration. Table 3 shows the effects of 2-phenylethanol on the ethanol production of Saccharomyces cerevisiae under different inoculation amounts of Lactobacillus plantarum. It can be seen from Table 3 that the larger the inoculation amount of Lactobacillus plantarum, the more serious the contamination of Saccharomyces cerevisiae ethanol fermentation and the lower the ethanol production. And under different inoculation amounts, adding 120 mg / L 2-phenylethanol has a promoting effect on ethanol production, and the lower the inoculation amount of Lactobacillus plantarum, the more obvious this promoting effect is.

[0049] Table 3 Effects of 2-phenylethanol on the ethanol production of Saccharomyces cerevisiae under different inoculation amounts of Lactobacillus plantarum

[0050]

[0051] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by quorum sensing, characterized in that The method is to inoculate Saccharomyces cerevisiae GIM2.188 at an inoculum size of (1 - 4)×10 5 cells / mL into YPD medium containing 120 mg / L of 2-phenylethanol, and ferment and culture at 28 °C and 180 rmp / min for 9 - 12 h; or inoculate Saccharomyces cerevisiae GIM2.188 and Lactobacillus plantarum at inoculum sizes of (1 - 4)×10 5 cells / mL and 1×10 6 ~1×10 8 cells / mL respectively into YPD medium containing 120 mg / L of 2-phenylethanol, and ferment and culture at 28 °C and 180 rmp / min for 9 - 12 h to achieve the improvement of ethanol production and the reduction of the harm of bacterial contamination; the bacteria in the harm of bacterial contamination are of the genus Lactobacillus.

2. The method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing according to claim 1, characterized in that The inoculum amount of the Saccharomyces cerevisiae GIM2.188 is to inoculate the Saccharomyces cerevisiae GIM2.188 into YPD medium and culture it at 28 °C and 180 rmp / min for 9 to 12 h for activation. The activated strain is inoculated into YPD medium again and cultured for 9 to 12 h, and is determined by a hemocytometer according to (1 to 4) × 10 5 cells / mL.

3. The method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing according to claim 1, wherein The inoculation amount of the Lactobacillus plantarum is to inoculate Lactobacillus plantarum ATCC8014 into MRS medium, statically activate and culture it in a constant temperature incubator at 37 °C for 9-12 h. The activated strain is inoculated into MRS medium again and cultured for 9-12 h, and is determined by the dilution coating method to be 1×10 6 ~1×10 8 cells / mL.

4. The method for promoting Saccharomyces cerevisiae to increase ethanol production and reduce the harm of bacterial contamination by using quorum sensing according to claim 1, characterized in that The Lactobacillus genus includes Lactobacillus plantarum ACCC 8014, Lactobacillus plantarum ACCC 11095, Lactobacillus acidophilus GDMCC 1.731, Lactobacillus brevis GDMCC 1.773, Lactobacillus plantarum GDMCC 1.2868, Lactobacillus casei GDMCC 1.2885, and Lactobacillus acidophilus GDMCC 1.1807.

Images