CN112410257B

CN112410257B - Microbial agent for inhibiting pathogenic bacteria in bottom mud of circulating water system and method thereof

Info

Publication number: CN112410257B
Application number: CN202011348379.7A
Authority: CN
Inventors: 牟宗艳; 潘晓洁; 杨财贵
Original assignee: Beijing Changxing Taihua Technology Development Co ltd
Current assignee: Beijing Changxing Taihua Technology Development Co ltd
Priority date: 2020-11-26
Filing date: 2020-11-26
Publication date: 2022-05-20
Anticipated expiration: 2040-11-26
Also published as: CN112410257A

Abstract

The invention relates to the field of water environment protection, in particular to a microbial agent for inhibiting pathogenic bacteria in bottom mud of a circulating water system and a method thereof. According to the volume percentage, the microbial inoculum consists of 10 to 15 percent of saccharomyces cerevisiae fermentation liquor, 15 to 20 percent of bacillus subtilis fermentation liquor, 15 to 20 percent of bacillus thuringiensis fermentation liquor, 15 to 20 percent of dead bacillus vallisae fermentation liquor and 35 to 40 percent of lactobacillus plantarum fermentation liquor. The scheme adopts a means of combining and using various microorganisms, and solves the technical problem that a single strain is difficult to inhibit pseudomonas aeruginosa and aeromonas in bottom mud of a circulating water system. The microbial agent can be applied to practical operations such as pathogenic bacteria treatment in an industrial circulating water system.

Description

Microbial agent for inhibiting pathogenic bacteria in bottom mud of circulating water system and method thereof

Technical Field

The invention relates to the field of water environment pollution treatment, in particular to a microbial agent for inhibiting pathogenic bacteria in bottom mud of a circulating water system and a method thereof.

Background

With the rapid development of industries in recent years, the water consumption of industrial enterprises is greatly increased, wherein a circulating cooling water system generally accounts for more than 60% of the industrial water consumption, and the water consumption in the industries such as electric power, chemical engineering and the like is more than 70% -80%. The ion concentration of the cooling water is increased in the evaporation process, and meanwhile, the cooling water is in contact with the outside air, and microorganisms and other pollutants in the air also continuously enter the system, so that the problems of bacterial-algae outbreak, scaling, corrosion and the like of a circulating water system occur. The traditional treatment method can generate secondary pollution if a phosphorus-containing chemical agent or a low-phosphorus chemical agent is added, while the microbial preparation is a circulating water treatment method emerging in recent years, and the microbial preparation is formed by using low-corrosivity microorganisms and high-efficiency degrading and flocculating microorganisms according to the concepts of low nutrient limitation, ecological niche competitive exclusion and the like, has the advantages of environmental friendliness, thorough degradation and the like, and is gradually applied to various industrial industries.

The discharge standard of the circulating water of industrial enterprises is more and more strict, and the treatment cost is more and more high. In order to reduce the subsequent treatment cost, enterprises tend to improve the treatment efficiency of the circulating water to reach the relevant standard of directly discharging the circulating water into natural water bodies or town pipe networks. While various medicaments are used for stabilizing the water quality, pathogenic bacteria which flow into the circulating water system through natural water and are enriched in bottom mud of the circulating water system are often ignored and directly discharged. The pathogenic bacteria in natural water are usually aeromonas, pseudomonas aeruginosa, avian mycobacterium tuberculosis and the like, and most of the pathogenic bacteria are opportunistic pathogenic bacteria or conditional pathogenic bacteria, namely, the pathogenic bacteria can cause diseases under certain conditions, and for example, the pathogenic bacteria have higher pathogenic possibility for people with wounds, people with autoimmune defects and the like. Besides gastrointestinal diseases caused by oral ingestion, the pathogenic bacteria can also be infected by means of skin or organ contact, aerosol inhalation and the like. Therefore, pathogenic bacteria in the natural water body directly harm the health of urban residents, and the inhibition of the pathogenic bacteria in the bottom mud of the circulating water system needs to be paid attention to prevent the pathogenic bacteria from being directly discharged into the natural water body or an urban drainage system. In the prior art, some microbial strains capable of inhibiting pathogenic bacteria have been reported and applied to practical operation of water body pathogenic bacteria treatment, but the effect of using a single strain to treat the pathogenic bacteria in the water body is limited, so that the balance of the microorganisms in an ecological system is difficult to maintain, and the pathogenic bacteria still cannot be effectively inhibited.

Disclosure of Invention

The invention aims to provide a microbial agent for inhibiting pathogenic bacteria in bottom sediment of a circulating water system and a method thereof, and aims to solve the technical problem that a single strain is difficult to inhibit the pathogenic bacteria in the bottom sediment of the circulating water system.

In order to achieve the purpose, the invention adopts the following technical scheme:

a microbial agent for inhibiting pathogenic bacteria in bottom mud of a circulating water system comprises, by volume, 10% -15% of a saccharomyces cerevisiae fermentation broth, 15% -20% of a bacillus subtilis fermentation broth, 15% -20% of a bacillus thuringiensis fermentation broth, 15% -20% of a dead bacillus vallismortis fermentation broth and 35% -40% of a lactobacillus plantarum fermentation broth.

The principle and the advantages of the scheme are as follows: in the scheme, the microbial agent jointly used by bacillus, lactobacillus and saccharomyces cerevisiae is adopted, and the combination of several microbes can mutually promote and cooperate, so that various inhibition mechanisms are fully exerted, and the inhibition on pathogenic bacteria in sludge (sewage) of a circulating water system is realized.

The bacillus used in the scheme has strong degradation capability and competes with pathogenic bacteria for carbon sources and energy sources. The bacillus generally has rich enzyme systems such as protease, lipase, cellulase, amylase and the like, and can decompose most organic matters. Can compete with various pathogenic bacteria for the colonization sites in the environment, and inhibits the growth of the pathogenic bacteria by consuming the nutrients such as carbon source, energy source and the like in the water body and the bottom sediment. In addition, by degrading COD, ammonia nitrogen and the like in the system, the tendency of bacterial-algae outbreak, scaling and corrosion of the whole circulating water system can be effectively reduced. In addition, bacillus strains are highly viable and secrete antimicrobial substances. The bacillus is aerobic or facultative anaerobic, has simple nutrition requirement, fast propagation and strong adaptability, can form a spore structure in severe environment and can recover growth in environment with proper conditions. The bacteriostatic substances in the secondary metabolites are mainly lipopeptide (lipopeptide) compounds, mainly comprise surfactin (surfactin), iturin (iturin) and fengycin (fengycin)3, generally have the effects of inhibiting bacteria, fungi, viruses and mycoplasma, and have important research significance on the prevention and treatment of diseases caused by fungi or viruses.

In this scheme, the inventors used killed B.oryzae in addition to conventional B.subtilis and B.thuringiensis. After the dead bacillus vallismortis is added into the microbial agent, the inhibition capability of pseudomonas aeruginosa of the microbial agent is obviously enhanced, and the inhibition capability is obviously better than that of a microbial agent composition without dead bacillus vallismortis and that of dead bacillus vallismortis singly added. The inventor analyzes that the reason for the phenomenon is that the dead bacillus vallismortis produces certain biochemical reasons or physical reasons through metabolism, has promotion effect on growth and proliferation of bacillus subtilis and bacillus thuringiensis and secretion of bacteriostatic substances, further increases the competitive effect of bacillus on carbon sources and the like of pathogenic bacteria, and further enhances the bacteriostatic effect of bacillus.

The process of lactobacillus plantarum producing lactic acid can reduce the pH value, inhibit the growth of pathogenic bacteria such as escherichia coli, salmonella and the like, and simultaneously reduce the pH value in the system, so that the problems of high alkalinity and easy scaling of the system when the concentration multiple is increased can be remarkably relieved. The lactobacillus is a typical probiotic, is widely applied to industries such as food, agriculture, medical treatment and the like, and has extremely high safety. In addition, pathogenic bacteria can also be inhibited by a strategy such as low nutrient limitation.

The lactobacillus is an auxotrophic strain, and the yeast not only secretes protease and lipase, decomposes substrates to produce a plurality of nutrient substances such as amino acid, vitamin and the like to promote the proliferation of the lactobacillus, but also utilizes lactate metabolized by the lactobacillus as an energy substance for metabolism. In addition, lactobacillus can break down lactose (which is not normally available to yeast) into galactose and glucose to provide a carbon source for yeast. The yeast is mainly used in brewing wine and food industries, and has extremely high safety. In addition, the yeast has strong proteolytic and lipolytic activity, organic acids such as propionic acid, lactic acid and ascorbic acid and toxin protein can be produced by fermentation, and the metabolites can inhibit the growth of pathogenic bacteria.

The microbial inoculum can be applied to the treatment of industrial circulating cooling water, which can be called industrial circulating water and circulating water. Industrial circulating cooling water is mainly used in cooling water systems, and a system for cooling a process medium with water is called a cooling water system.

Further, the fermentation liquor comprises 12% of saccharomyces cerevisiae fermentation liquor, 16% of bacillus subtilis fermentation liquor, 17% of bacillus thuringiensis fermentation liquor, 18% of dead bacillus vallismortis fermentation liquor and 37% of lactobacillus plantarum fermentation liquor in percentage by volume. The microbial agent prepared according to the proportion can effectively inhibit pseudomonas aeruginosa in sewage.

Further, the fermentation liquor comprises, by volume, 10% of saccharomyces cerevisiae fermentation liquor, 15% of bacillus subtilis fermentation liquor, 15% of bacillus thuringiensis fermentation liquor, 20% of dead bacillus vallismortis fermentation liquor and 40% of lactobacillus plantarum fermentation liquor. The microbial agent prepared according to the proportion can effectively inhibit pseudomonas aeruginosa and aeromonas in sewage.

Further, in the microbial agent, bacillus subtilis and bacillus thuringiensisThe effective viable count of bacteria, dead Bacillus cereus and Lactobacillus plantarum is 0.6 × 10⁹—1.5×10⁹cfu/ml. The effective viable count can ensure that the bacillus subtilis, the bacillus thuringiensis, the dead bacillus vallismortis and the lactobacillus plantarum can effectively inhibit pathogenic bacteria in sewage.

Furthermore, in the microbial agent, the effective viable count of the saccharomyces cerevisiae is 4 multiplied by 10⁷cfu/ml. The effective viable count can ensure that the saccharomyces cerevisiae can effectively play a role in inhibiting pathogenic bacteria in sewage.

Further, the method comprises the step of compounding the microbial inoculum: mixing the OD in proportions₆₀₀And (3) 0.9-1.1 of saccharomyces cerevisiae fermentation liquor, bacillus subtilis fermentation liquor, bacillus thuringiensis fermentation liquor, dead bacillus vallismortis fermentation liquor and lactobacillus plantarum fermentation liquor to obtain the microbial agent. OD of fermentation broth₆₀₀When the value is 0.9-1.1, the concentration and the quantity of each microorganism meet the requirement of the microbial inoculum, and the effect of jointly inhibiting pathogenic bacteria can be realized.

Further, the method comprises a strain activating step and a first-stage seed culture step which are sequentially carried out before the step of compounding the microbial inoculum; in the strain activating step, LB solid culture medium is used for respectively activating bacillus subtilis, bacillus thuringiensis and dead bacillus vallismortis, MRS solid culture medium is used for activating lactobacillus plantarum, PDA solid culture medium is used for activating saccharomyces cerevisiae, and activated bacillus subtilis strain, activated bacillus thuringiensis strain, activated dead bacillus vallismortis strain, activated lactobacillus plantarum strain and activated saccharomyces cerevisiae strain are obtained. By adopting the technical scheme, the solid culture medium is used for respectively activating the microbial strains in the scheme, so that the growth and proliferation activity of the microorganisms can be promoted to be recovered, and conditions are created for obtaining a large amount of target microorganisms subsequently.

Further, in the first-stage seed culture step, respectively amplifying the activated bacillus subtilis strain, the activated bacillus thuringiensis strain and the activated dead bacillus vallismortis strain by using an LB liquid culture medium to obtain bacillus subtilis fermentation liquor, bacillus thuringiensis fermentation liquor and dead bacillus vallismortis fermentation liquor; amplifying the activated lactobacillus plantarum by using an MRS liquid culture medium to obtain lactobacillus plantarum fermentation liquor; and (3) amplifying the activated saccharomyces cerevisiae by using a PDA liquid culture medium to obtain saccharomyces cerevisiae fermentation liquor. By adopting the technical scheme, the fermentation liquor with the activity and the microorganism quantity meeting the requirements can be obtained through primary seed culture.

Further, in the first-stage seed culture step, the amplification conditions of the activated lactobacillus plantarum are as follows: standing at 30-32 deg.C for culture; the amplification conditions of the activated bacillus subtilis, the activated bacillus thuringiensis, the activated dead bacillus vallismortis and the activated saccharomyces cerevisiae are as follows: culturing at 28-32 deg.C in a shaker at rotation speed of 120-. By using the above culture conditions, various microorganisms can be sufficiently proliferated and maintained in a good active state.

Further, when the microbial agent is used for treating industrial circulating cooling water, the first adding amount of the microbial agent is 0.1-0.4% of the retained water amount, and the daily adding amount of the microbial agent is 0.01-0.1% of the retained water amount. By adopting the method and the dosage, good bacteriostasis effect can be achieved, and the inhibition rate to aeromonas and the inhibition rate to pseudomonas aeruginosa can reach ideal levels. The use amount is too low to form effective interference on the original microbial community in the water body. The use amount is too high, so that the medicament cost of enterprises is increased, and the production amount of the microbial inoculum cannot keep up with the demand amount.

Detailed Description

The following is further detailed by way of specific embodiments:

example 1:

the microbial agent for inhibiting pathogenic bacteria in the bottom mud of the circulating water system comprises the following components in percentage by volume:

the strains are purchased from China center for culture collection and management of industrial microorganisms, wherein the preservation number of the saccharomyces cerevisiae is CICC 1002; the preservation number of the bacillus subtilis is CICC 24713; the Bacillus thuringiensis is deposited with the number CICC 21298; the deposit number of the dead bacillus vallismortis CICC 21346; the lactobacillus plantarum deposit number is CICC 10481.

The preparation method of the composite deodorant comprises the following steps:

(1) activating the strain: respectively inoculating bacillus subtilis, bacillus thuringiensis and dead bacillus vallismortis to an LB solid culture medium, respectively inoculating lactobacillus plantarum to an MRS solid culture medium, respectively inoculating saccharomyces cerevisiae to a PDA solid culture medium, and standing and culturing in a constant-temperature culture box. The culture conditions were 28 ℃ and the culture time was 24 h. The LB solid medium, MRS solid medium, and PDA solid medium are all common media in the prior art, and are not described herein. After activated culture, the activated bacillus subtilis strain, the activated bacillus thuringiensis strain, the activated dead bacillus oryzae strain, the activated lactobacillus plantarum strain and the activated saccharomyces cerevisiae strain are obtained.

(2) First-order seed culture: selecting single colonies of the activated strain obtained in the step (1) and inoculating the single colonies into a corresponding liquid culture medium. Namely, bacillus subtilis, bacillus thuringiensis and dead bacillus vallismortis are respectively inoculated in an LB liquid culture medium, lactobacillus plantarum is inoculated in an MRS liquid culture medium, and saccharomyces cerevisiae is inoculated in a PDA liquid culture medium, and primary seed culture is respectively carried out. The culture conditions of the lactobacillus plantarum are as follows: standing and culturing at 32 ℃ in an incubator; the culture conditions of other bacteria were: the cells were incubated at 32 ℃ in a shaker at 120 rpm. Culturing for 24h (or culturing for 24-36h in actual culture) to obtain Bacillus subtilis primary seed solution, Bacillus thuringiensis primary seed solution, dead Bacillus oryzae primary seed solution, Lactobacillus plantarum primary seed solution, and Saccharomyces cerevisiae primary seed solution.

(3) Compounding the microbial inoculum: respectively inoculating the five first-stage seed solutions obtained in the step (2) into corresponding liquid culture media, wherein the inoculation amount is 5% (v/v), and culturingTo OD₆₀₀Stopping culturing when the value is 1 to obtain Bacillus subtilis fermentation liquor, Bacillus thuringiensis fermentation liquor, dead Bacillus oryzae fermentation liquor, Lactobacillus plantarum fermentation liquor and Saccharomyces cerevisiae fermentation liquor. The five fermentation liquors are mixed according to a proportion and uniformly mixed to obtain the microbial agent. Due to control of OD₆₀₀The value is 1, so that the effective viable count of the bacillus subtilis, the Alcaligenes faecalis, the Gordonia friendship and the lactobacillus casei in the microbial fermentation broth is 0.6 multiplied by 10⁹—1.5×10⁹cfu/ml, effective viable count of Saccharomyces cerevisiae is 4 × 10⁷cfu/ml。

Example 2:

this example is basically the same as example 1, except that the formulation is slightly adjusted, and in this example, the composition (in volume percent) of the microbial agent for inhibiting pathogenic bacteria in the bottom sediment of the circulating water system is:

in "(1) the activated strain", the culture conditions were 27 ℃.

In the "(2) first-order seed culture", the culture conditions of lactobacillus plantarum were: standing and culturing at 30 ℃ in an incubator; the culture conditions of other bacteria were: culturing at 28 deg.C in shaker at 180 rpm.

In (3) microbial inoculum Recompounded, the OD of each strain₆₀₀The culture was stopped at a value of 1.1.

Example 3:

in the "(1) activated strain", the culture conditions were 32 ℃.

In (3) compounding of microbial inoculumOD of each strain₆₀₀The culture was stopped at a value of 0.9.

Example 4:

experimental example 1: test of effect of microbial inoculum in laboratory

A small test reactor is arranged in a laboratory to measure the effect of the preparation on inhibiting pathogenic bacteria, and the specific detection method comprises the following steps:

1. experimental samples:

a: the microbial preparation of the invention;

b: the microbial preparation of the present invention (microbial preparation in which A is inactivated under the inactivation condition of 1.05 kg/cm)²Autoclaving at 121.3 ℃ for 20 minutes);

c: control treating agents (12% of saccharomyces cerevisiae fermentation liquor, 16% of bacillus subtilis fermentation liquor, 17% of bacillus thuringiensis fermentation liquor, 18% of dead bacillus vallisensis fermentation liquor substitutes (9% of each of the bacillus subtilis fermentation liquor and the bacillus thuringiensis fermentation liquor), and 37% of lactobacillus plantarum fermentation liquor);

d: control treatment (sterile water).

In this embodiment, the microbial preparation formulation of the present invention comprises, by volume: 12% of saccharomyces cerevisiae fermentation liquor, 16% of bacillus subtilis fermentation liquor, 17% of bacillus thuringiensis, 18% of dead bacillus vallismortis and 37% of lactobacillus plantarum fermentation liquor (namely, the microbial agent in the embodiment 1).

The detection method comprises the following steps: taking bottom mud and water in a reservoir taken by a certain Tianjin power plant as test objects (only Pseudomonas aeruginosa is detected in original bottom mud and water samples), 4 cylindrical reactors of 5L are arranged. In order to simulate the working condition on site, the water temperature is kept at 20-30 ℃ by using a heating rod, the concentration multiple is kept at 2.5-3.5, the stirrer is continuously stirred, and a shower head with the height of 0.5m is used for simulating the spraying effect of the cooling tower. On the first day of the test, 0.4% by volume of test agent A, B, C and D (20 mL each) were added for the first time. Thereafter, test agents A, B, C and D were added at 0.1% volume ratio every 10 days (5 mL of each reagent was added). The test lasts for 60 days, 500mL of water sample and sediment mixture are taken every 20 days for microbial diversity analysis, and the proportion change (percentage) of pseudomonas aeruginosa and the inhibition rate of the pseudomonas aeruginosa are determined (calculation method: inhibition rate is (0 day proportion-60 day proportion)/0 day proportion multiplied by 100%).

Table 1: percentage of pseudomonas aeruginosa and inhibition rate.

The results in table 1 show that the microbial preparation of the present invention has good inhibition effect on pseudomonas aeruginosa in circulating water system at 20 days, 40 days and 60 days, and is obviously superior to blank control and commercial circulating water stabilizer. Compared with the C, the antibacterial effect is improved by 38.43%, and the synergistic effect of the dead bacillus vallismortis and other strains is reflected (the dead bacillus vallismortis does not have an obvious inhibition effect on pseudomonas aeruginosa by previous experimental detection).

Experimental example 2: bacteria agent effect test of circulating water dynamic simulation system

The circulating water dynamic simulation system in a certain factory area of the sand flat dam in Chongqing is used for measuring the effect of the microbial inoculum in a pilot test system, and the specific detection method comprises the following steps:

1. experimental samples: the experimental group was a microbial preparation of the invention (prepared in example 2) and the control group was ultrapure water (sterilized)

In this embodiment, the microbial preparation formulation of the present invention comprises, by volume: 10% of saccharomyces cerevisiae fermentation liquor, 15% of bacillus subtilis fermentation liquor, 15% of bacillus thuringiensis, 20% of dead bacillus vallismortis and 40% of lactobacillus plantarum fermentation liquor.

2. The detection method comprises the following steps: the bottom mud and water of the Yangtze river section of Chongqing Sharpa dam are used as test objects (Aeromonas spp, Pseudomonas aeruginosa are detected in the original bottom mud and water sample). The device is a parallel two-set system, and the volume of each system is 100L (the volume of the water is called as the water holding quantity of industrial circulating cooling water (system)). In order to simulate the working condition on site, the speed of the circulating pump is set to be 1.0m/s, and the concentration multiple is 3.0. On the first day of the test, the test agent is added according to the volume ratio of 0.2 percent of the first adding (namely 200mL of the test agent is added respectively, the adding is called as the first adding, and the first adding amount can be 0.1 to 0.4 percent of the water retention amount). And then supplementing the test agent by 0.05% of volume ratio every 10 days (namely 50mL, which is called daily addition, and performing daily addition every 10 days after the initial addition, wherein the daily addition can be 0.01% -0.1% of the retained water amount). The test lasts for 45 days, 500mL of water sample and sediment mixture are taken every 15 days for microbial diversity analysis, the ratio change (thousandths) of aeromonas and pseudomonas aeruginosa is determined, and the inhibition rate is calculated (calculation method: inhibition rate is (0 day ratio-45 day ratio)/0 day ratio x 100%).

The experimental example simulates the actual operation of treating a circulating water system by using the microbial agent, and the adding mode and the dosage of the microbial agent are as follows: the first adding amount of the microbial agent is 0.1-0.4% of the water retention amount of the circulating water system; the daily adding amount of the microbial agent is 0.01-0.1% of the water retaining amount of the circulating water system. By adopting the method and the dosage, good bacteriostatic effect can be achieved, the inhibition rate on aeromonas can reach more than 50%, and the inhibition rate on pseudomonas aeruginosa can reach more than 40%.

Table 2: thousandths and inhibition rates of aeromonas

Table 3: amesdial and inhibition rate of pseudomonas aeruginosa

The results in tables 2 and 3 show that the microbial preparation of the present invention shows good inhibitory effects on both Aeromonas spp and Pseudomonas aeruginosa in dynamic simulation experiments of complex conditions similar to those in the field. After the experimental period is finished, the inhibition rates respectively reach 55.61% and 47.96%, which are obviously superior to those of a control group, and the risk that pathogenic bacteria in a circulating water system flow into a natural water body can be greatly reduced. In addition to the bacteriostatic tests performed on the microbial agents prepared in examples 1 and 2, the inventors also performed experimental tests of the present experimental example using the microbial agents prepared in examples 3 and 4, and the microbial agents prepared in examples 3 and 4 also showed good inhibitory effects on both Aeromonas spp and Pseudomonas aeruginosa. The microbial agent comprises, by volume, 10-15% of saccharomyces cerevisiae fermentation liquor, 15-20% of bacillus subtilis fermentation liquor, 15-20% of bacillus thuringiensis fermentation liquor, 15-20% of dead bacillus oryzae fermentation liquor and 35-40% of lactobacillus plantarum fermentation liquor, and can be applied to practical operation of inhibiting pathogenic microorganisms in sewage.

The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.

Claims

1. A microbial agent for inhibiting pathogenic bacteria in bottom mud of a circulating water system is characterized in that: according to the volume percentage, the fermentation liquid consists of 10 to 15 percent of saccharomyces cerevisiae fermentation liquid, 15 to 20 percent of bacillus subtilis fermentation liquid, 15 to 20 percent of bacillus thuringiensis fermentation liquid, 15 to 20 percent of dead bacillus vallisae fermentation liquid and 35 to 40 percent of lactobacillus plantarum fermentation liquid.

2. The microbial inoculant for inhibiting pathogenic bacteria in bottom sludge of a circulating water system according to claim 1, wherein the microbial inoculant comprises: the fermentation liquor consists of 12 percent of saccharomyces cerevisiae fermentation liquor, 16 percent of bacillus subtilis fermentation liquor, 17 percent of bacillus thuringiensis fermentation liquor, 18 percent of dead bacillus vallismortis fermentation liquor and 37 percent of lactobacillus plantarum fermentation liquor in percentage by volume.

3. The microbial inoculant for inhibiting pathogenic bacteria in bottom sludge of a circulating water system according to claim 1, wherein the microbial inoculant comprises: the fermentation liquor consists of 10 percent of saccharomyces cerevisiae fermentation liquor, 15 percent of bacillus subtilis fermentation liquor, 15 percent of bacillus thuringiensis fermentation liquor, 20 percent of dead bacillus vallismortis fermentation liquor and 40 percent of lactobacillus plantarum fermentation liquor in percentage by volume.

4. The microbial inoculant for inhibiting pathogenic bacteria in the bottom sludge of a circulating water system according to claim 2 or 3, wherein: in the microbial agent, the effective viable count of bacillus subtilis, bacillus thuringiensis, dead bacillus vallismortis and lactobacillus plantarum is 0.6 multiplied by 10⁹—1.5×10⁹cfu/ml。

5. The microbial inoculant for inhibiting pathogenic bacteria in the bottom sludge of a circulating water system according to claim 4, wherein: in the microbial agent, the effective viable count of the saccharomyces cerevisiae is 4 multiplied by 10⁷cfu/ml。

6. A circulating water system ground for inhibition according to claim 5The preparation method of the microbial agent of the pathogenic bacteria in the mud is characterized by comprising the following steps: comprises the step of compounding microbial inoculum: mixing the OD in proportions₆₀₀And (3) 0.9-1.1 of saccharomyces cerevisiae fermentation liquor, bacillus subtilis fermentation liquor, bacillus thuringiensis fermentation liquor, dead bacillus vallismortis fermentation liquor and lactobacillus plantarum fermentation liquor to obtain the microbial agent.

7. The method for preparing the microbial inoculum for inhibiting pathogenic bacteria in the bottom sludge of the circulating water system according to claim 6, which is characterized in that: before the step of compounding the microbial inoculum, the method comprises a step of activating strains and a step of culturing first-level seeds which are sequentially carried out; in the strain activating step, LB solid culture medium is used for respectively activating bacillus subtilis, bacillus thuringiensis and dead bacillus vallismortis, MRS solid culture medium is used for activating lactobacillus plantarum, PDA solid culture medium is used for activating saccharomyces cerevisiae, and activated bacillus subtilis strain, activated bacillus thuringiensis strain, activated dead bacillus vallismortis strain, activated lactobacillus plantarum strain and activated saccharomyces cerevisiae strain are obtained.

8. The method for preparing the microbial inoculum for inhibiting pathogenic bacteria in the bottom sludge of the circulating water system according to claim 7, which is characterized in that: in the first-stage seed culture step, respectively amplifying the activated bacillus subtilis strain, the activated bacillus thuringiensis strain and the activated dead bacillus vallismortis strain by using an LB liquid culture medium to obtain bacillus subtilis fermentation liquor, bacillus thuringiensis fermentation liquor and dead bacillus vallismortis fermentation liquor; amplifying the activated lactobacillus plantarum by using an MRS liquid culture medium to obtain lactobacillus plantarum fermentation liquor; and (3) amplifying the activated saccharomyces cerevisiae by using a PDA liquid culture medium to obtain saccharomyces cerevisiae fermentation liquor.

9. The method for preparing the microbial inoculum for inhibiting pathogenic bacteria in the bottom sludge of the circulating water system according to claim 8, which is characterized in that: in the first-stage seed culture step, the amplification conditions of the activated lactobacillus plantarum are as follows: standing at 30-32 deg.C for culture; the amplification conditions of the activated bacillus subtilis, the activated bacillus thuringiensis, the activated dead bacillus vallismortis and the activated saccharomyces cerevisiae are as follows: culturing at 28-32 ℃ in a shaker at the rotation speed of 120-180 rpm.

10. The microbial inoculant for inhibiting pathogenic bacteria in the bottom sludge of a circulating water system according to claim 5, wherein: when the microbial agent is used for treating industrial circulating cooling water, the first adding amount of the microbial agent is 0.1-0.4% of the retained water amount, and the daily adding amount of the microbial agent is 0.01-0.1% of the retained water amount.