CN117511925A

CN117511925A - Microbial agent, preparation method and application thereof, and method for preventing and controlling crop pathogenic bacteria

Info

Publication number: CN117511925A
Application number: CN202311469183.7A
Authority: CN
Inventors: 魏浩; 王莹; 金晶; 邓祖科; 车欣宇; 吴书凤; 张鑫鹏; 周士龙
Original assignee: Beijing Century Amms Biological Engineering Co ltd
Current assignee: Beijing Century Amms Biological Engineering Co ltd
Priority date: 2023-11-07
Filing date: 2023-11-07
Publication date: 2024-02-06

Abstract

The application relates to the technical field of microbial application, and in particular discloses a microbial agent, a preparation method and application thereof, and a method for preventing and controlling crop pathogenic bacteria. The microbial agent comprises a carrier and pseudomonas aeruginosa with the preservation number of CGMCC No.28235 loaded on the carrier. The microbial agent provided by the application can keep the effective viable count in the microbial agent for a long time, and can effectively reduce the occurrence of crop diseases, and especially can improve, prevent and control peanut southern blight, tomato blight and potato scab.

Description

Microbial agent, preparation method and application thereof, and method for preventing and controlling crop pathogenic bacteria

Technical Field

The application relates to the technical field of microbial application, in particular to a microbial agent, a preparation method and application thereof, and a method for preventing and controlling crop pathogenic bacteria.

Background

In recent years, the effects of crop disease on crop yield have tended to increase year by year. At present, the prevention and control measures for crop diseases mainly comprise rotation, deep ploughing, cultivation of resistant varieties, chemical agent use and the like. However, the prevention and control modes can both treat the symptoms and the root causes, and the long-term use of chemical agents can also lead to the pollution of field soil by the chemical agents, so that the quality and the yield of agricultural products are reduced, and even the safety problem of the agricultural products can also occur.

Based on the above, the prevention and control of crop diseases by using microbial agents is a problem which has been urgently needed to be solved in the green development of agriculture. The microbial agent and downstream products thereof are not separated from the discovery and industrialized fermentation of microbial strains. Therefore, it is required to obtain a larger variety and number of biocontrol strains, and develop a larger number of novel microbial agents based on the biocontrol strains while enriching the flora structure of crop disease prevention and control strains so as to meet the requirements of healthy growth of crops, stable crop yield and long-term green development of agriculture.

Disclosure of Invention

The application provides a microbial agent, a preparation method and application thereof, and a method for preventing and controlling pathogenic bacteria of crops. The microbial agent provided by the application can keep the effective viable count in the microbial agent for a long time, and can effectively reduce the occurrence of crop diseases, and especially can improve, prevent and control peanut southern blight, tomato blight and potato scab.

In a first aspect, the present application provides a microbial agent, which adopts the following technical scheme:

the microbial agent comprises a carrier and pseudomonas aeruginosa with the preservation number of CGMCC No.28235 which is loaded on the carrier.

The microbial agent comprises a carrier and pseudomonas aeruginosa. The carrier and the pseudomonas aeruginosa have the functions of pathogenic bacteria on crops and the pathogenic bacteria on the crops after being matched, so that the occurrence of crop diseases is reduced.

In this application, the carrier may be a particulate material capable of supporting the microorganism. On the one hand, the microorganism is loaded on a carrier and is used as a vector of the microorganism acting on farmlands, crops or pathogenic bacteria, and the microorganism and the crop pathogenic bacteria form a competition relationship in a micro-ecological system or inhibit the growth of the crop pathogenic bacteria in the micro-ecological system by utilizing the microorganism so as to prevent the growth and propagation of the crop pathogenic bacteria, thereby reducing the occurrence of crop diseases, namely improving, preventing and controlling the occurrence of the crop diseases by blocking the occurrence way of the crop diseases. On the other hand, due to the self adsorption effect, the carrier can directly adsorb crop pathogenic bacteria on the main body of the carrier, so that the contact and connection between crop pathogenic bacteria and farmlands and crops are reduced, and then the occurrence of crop diseases is reduced, namely the occurrence of crop diseases is improved, prevented and controlled by blocking the source of the crop diseases.

Pseudomonas aeruginosa (Pseudomonas chlororaphis) in the application is preserved in China general microbiological culture Collection center (CGMCC) with the preservation number of CGMCC No.28235 and the preservation address of the pseudomonas aeruginosa at the month 8 and 23 of 2023: no. 1 and No. 3 of the north cinquefoil of the morning sun area of beijing city. The vegetative cells of the strain are rod-shaped and gram-negative. The optimal growth temperature is 30 ℃, the highest growth temperature is 35 ℃, the lowest growth temperature is 20 ℃, and the aerobic is carried out. Colonies cultured in nutrient agar medium at 30deg.C for 48 hr are orange-yellow, opaque, rough in surface, and wrinkled at edges. The strain has good prevention and control effects on peanut southern blight, tomato fusarium wilt and potato scab.

The microbial agent composed of the carrier and the pseudomonas aeruginosa with the preservation number of CGMCC No.28235 can obviously improve the prevention and control effect on crop pathogenic bacteria under the combined action of the carrier and the pseudomonas aeruginosa with the preservation number of CGMCC No.28235, and further the prevention and control effect on crop pathogenic bacteria by the microbial agent is far greater than that of the single carrier and the single pseudomonas aeruginosa with the preservation number of CGMCC No. 28235.

Optionally, the microbial agent is prepared by adopting the fermentation liquor of the pseudomonas aeruginosa and the carrier.

Optionally, the effective viable count of the pseudomonas aeruginosa in the microbial agent is 0.2-5 hundred million/g.

Optionally, the effective viable count of the pseudomonas aeruginosa in the microbial agent is 2-3 hundred million/g.

Optionally, the microbial agent is prepared by adopting the bacterial powder obtained after the pseudomonas aeruginosa is sprayed and dried and the carrier.

Optionally, the effective viable count of the pseudomonas aeruginosa in the microbial agent is 0.2-20 hundred million/g.

Optionally, the effective viable count of the pseudomonas aeruginosa in the microbial agent is 5-10 hundred million/g.

Optionally, in the spray drying, the air inlet temperature is 140-190 ℃, the feeding flow is 200-600L/h, and the atomization pressure is 0.1-0.5Mpa.

Optionally, the carrier is selected from any one or more of humic acid powder, diatomite, biochar, attapulgite powder, perlite and vermiculite.

Optionally, the carrier comprises biochar and humic acid powder.

Optionally, in the carrier, the weight ratio of the humic acid powder to the biochar is (0.2-5): 1.

optionally, in the carrier, the weight ratio of the humic acid powder to the biochar is (0.5-4): 1.

optionally, in the carrier, the weight ratio of the humic acid powder to the biochar is (1-2): 1.

in a specific embodiment, the weight ratio of the humic acid powder to the biochar in the carrier may be 0.2: 1. 0.25: 1. 0.3: 1. 0.5: 1. 1: 1. 2: 1. 3: 1. 4: 1. 5:1.

the biochar is a carbon-rich material, is formed by pyrolyzing an organic material under the condition of oxygen limitation or anaerobism, and has the characteristics of large specific surface area, pore structure, stable biochemical performance, strong adsorption capacity and the like.

Optionally, the carrier has a particle size of 120-250 μm.

In a second aspect, the present application provides a preparation method of a microbial agent, which adopts the following technical scheme:

the preparation method of the microbial agent specifically comprises the following steps:

and uniformly mixing the dried and sterilized carrier with pseudomonas aeruginosa with the preservation number of CGMCC No.28235 to obtain the microbial agent.

Optionally, the pseudomonas aeruginosa is fermentation broth of pseudomonas aeruginosa or fungus powder after pseudomonas aeruginosa spray drying.

In a third aspect, the present application provides the use of a microbial agent in the field of improving and controlling crop disease.

In a fourth aspect, the application provides application of a microbial agent in the fields of improvement and prevention of peanut southern blight, tomato blight and potato scab.

In a fifth aspect, the present application provides a method for controlling pathogenic bacteria of crops, which adopts the following technical scheme:

a method for preventing and controlling pathogenic bacteria of crops is characterized by that said microbial inoculum is applied to farmland in need of preventing and controlling pathogenic bacteria of crops.

Optionally, the microbial agent is prepared by utilizing the fermentation liquor of the pseudomonas aeruginosa, and the application amount of the microbial agent is 40-120 kg/mu when the effective viable count is 0.85-2.5 hundred million/g.

Optionally, the microbial agent is prepared by using the bacterial powder obtained after the pseudomonas aeruginosa is spray-dried, and when the effective viable count is 2.5-5 hundred million/g, the application amount of the microbial agent is 40-80 kg/mu.

In summary, the present application has the following beneficial effects:

1. the microbial agent provided by the application can improve, prevent and control peanut southern blight, tomato blight and potato scab.

2. The microbial agent provided by the application can keep the effective viable count in the microbial agent for a long time, so that the occurrence of crop diseases can be effectively reduced.

3. The microbial agent prepared from the bacterial powder obtained by spray drying of the pseudomonas aeruginosa fermentation broth can achieve 66.55% of prevention and control effects on tomato fusarium wilt pathogens, 72.03% of prevention and control effects on peanut southern blight pathogens and 61.58% of prevention and control effects on potato scab pathogens.

4. The microbial agent prepared by utilizing the pseudomonas aeruginosa fermentation broth has the effects of 71.24% on preventing and controlling pathogenic bacteria of tomato blight, 74.37% on preventing and controlling pathogenic bacteria of peanut southern blight and 63.21% on preventing and controlling pathogenic bacteria of potato scab.

Drawings

FIG. 1 shows the effective viable count of Pseudomonas aeruginosa fermentation broth after spray drying at different inlet air temperatures.

FIG. 2 shows the dry matter yields of Pseudomonas aeruginosa fermentation broth after spray drying at different inlet air temperatures.

FIG. 3 shows the effective viable count of Pseudomonas aeruginosa fermentation broth after spray drying at different feed rates.

FIG. 4 shows the dry matter yields of Pseudomonas aeruginosa fermentation broth after spray drying at different feed rates.

FIG. 5 shows the effective viable count of Pseudomonas aeruginosa fermentation broth after spray drying at various atomization pressures.

Detailed Description

The application provides a microbial agent, a preparation method and application thereof. The microbial agent provided by the application can keep the effective viable count in the microbial agent for a long time, and can effectively reduce the occurrence of crop diseases, and especially can improve, prevent and control peanut southern blight, tomato blight and potato scab.

Regarding microbial agents:

the microbial agent comprises a carrier and pseudomonas aeruginosa with the preservation number of CGMCC No.28235 loaded on the carrier.

Wherein, the fermentation liquor of pseudomonas aeruginosa and a carrier are adopted to prepare the microbial agent. The effective viable count of the pseudomonas aeruginosa in the microbial agent is 0.2-5 hundred million/g. Further, the effective viable count of Pseudomonas aeruginosa in the microbial agent is preferably 2-3 hundred million/g.

Wherein, the microbial agent is prepared by using the bacterial powder and the carrier of the pseudomonas aeruginosa after spray drying. The effective viable count of the pseudomonas aeruginosa in the microbial agent is 0.2-20 hundred million/g. Further, the effective viable count of Pseudomonas aeruginosa in the microbial agent is preferably 5-10 hundred million/g.

Wherein the carrier is selected from any one or more of humic acid powder, diatomite, biochar, attapulgite powder, perlite and vermiculite. Further, the carrier comprises humic acid powder and biochar. Still further, the weight ratio of humic acid powder to biochar in the carrier is (0.2-5): 1. the particle size of the carrier is 120-250 μm.

The preparation method of the microbial agent comprises the following steps:

the preparation method of the microbial agent specifically comprises the following steps: and uniformly mixing the dried and sterilized carrier with pseudomonas aeruginosa fermentation broth with the preservation number of CGMCC No.28235 to obtain the microbial agent. Wherein the Pseudomonas aeruginosa is fermentation broth of Pseudomonas aeruginosa or fungus powder of Pseudomonas aeruginosa after spray drying.

In addition, the application provides application of the microbial agent.

The microbial agent can be used for improving, preventing and controlling crop diseases, especially peanut southern blight, tomato wilt and potato scab.

The application also provides a method for preventing and controlling crop pathogenic bacteria, which is to apply the microbial inoculum to farmlands in need of preventing and controlling crop pathogenic bacteria. When the microbial agent is prepared by utilizing the fermentation broth of pseudomonas aeruginosa, the application amount of the microbial agent is 40-80 kg/mu. When the microbial agent is prepared by using the bacterial powder obtained after the pseudomonas aeruginosa is sprayed and dried, the application amount of the microbial agent is 40-80 kg/mu.

For the purposes, technical solutions and advantages of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to be within the scope of the present application.

Examples

Examples 1 to 8

Examples 1-8 each provide a microbial agent. The difference between the examples is the number of viable bacteria in the microbial agent, and the number is shown in Table 1.

(1) And (3) carrier treatment: sieving the carrier with 80 mesh sieve (180 μm) to obtain granule with certain particle size, oven drying, sterilizing at 121deg.C for 1 hr to obtain dried and sterilized carrier.

(2) Preparation of fermentation liquor:

the pseudomonas aeruginosa preserved at the temperature of minus 80 ℃ is transferred to a yeast extract culture medium (the formula of the culture medium is 4-6% of yeast extract, 10-20% of glucose, 1-3% of inorganic salt and purified water, and the pH value is 7) for culture until the logarithmic phase, and the pseudomonas aeruginosa is used as seed liquid. At a culture temperature of 30 ℃, the ventilation rate is as follows: can liquid loading = 0.8:1, culturing pseudomonas aeruginosa under the condition of 200rpm, fermenting for 30 hours, carrying out three-stage continuous tank transfer fermentation to obtain pseudomonas aeruginosa fermentation broth, and regulating the bacterial liquid concentration of the obtained fermentation broth to 50 hundred million/ml.

(3) Preparation of microbial inoculum

Mixing the dried and sterilized carrier with Pseudomonas aeruginosa fermentation broth with a preservation number of CGMCC No.28235 according to a weight ratio of 10:1, stirring for 30min by a machine at a stirring speed of 60 times/min, so that the carrier and the fermentation broth are uniformly mixed, and obtaining a microbial agent, wherein the effective viable count in the prepared microbial agent is shown in a table 1.

Examples 9 to 19

Examples 9-19 provide a microbial agent, respectively. The difference between the examples is the number of viable bacteria in the microbial agent, and the number is shown in Table 1.

The above embodiment differs from embodiments 1-8 in that: the microbial agent is prepared by mixing bacterial powder obtained by spray drying pseudomonas aeruginosa fermentation broth with a carrier.

(2) Preparation of fermentation liquor:

the pseudomonas aeruginosa preserved at the temperature of minus 80 ℃ is transferred to a yeast extract culture medium (the formula of the culture medium is 4-6% of yeast extract, 10-20% of glucose, 1-3% of inorganic salt and purified water, and the pH value is 7-8) for culture until the logarithmic phase, and the culture medium is used as seed liquid. At a culture temperature of 30 ℃, the ventilation rate is as follows: can liquid loading = 0.8:1, culturing pseudomonas aeruginosa under the condition of 200rpm, fermenting for 30 hours, carrying out three-stage continuous tank transfer fermentation to obtain pseudomonas aeruginosa fermentation broth, and regulating the bacterial liquid concentration of the obtained fermentation broth to 50 hundred million/ml.

And (3) carrying out centrifugal concentration on the pseudomonas aeruginosa fermentation broth, and then carrying out spray drying to obtain bacterial powder. The inlet air temperature of spray drying is 170 ℃, the feed flow is 400L/h, and the atomization pressure is 0.1Mpa. The effective viable count in the bacterial powder is 3.02X10 ¹¹ cfu/g, dry matter yield was 98%.

(3) Preparation of microbial inoculum

Mixing the fungus powder obtained by spray drying with a carrier according to a required proportion to obtain a microbial agent, wherein the effective viable count of the prepared microbial agent is shown in table 1.

Table 1 microbial agents provided in examples 1-19

Comparative example

Comparative example 1

Comparative example 1 provides an inhibitor. This comparative example differs from example 5 in that: only pseudomonas aeruginosa was included, no vector was included, as shown in table 1.

Comparative example 2

Comparative example 2 provides an inhibitor. This comparative example differs from example 13 in that: only pseudomonas aeruginosa was included, no vector was included, as shown in table 1.

Comparative example 3

Comparative example 3 provides an inhibitor. This comparative example differs from example 5 in that: only the vector was included, and pseudomonas aeruginosa was not included, as shown in table 1.

Performance test results 1

The microbial agents or inhibitors provided in examples 1 to 19 and comparative examples 1 to 3 were used as detection targets, and added into continuous cropping agricultural fields according to an application amount of 40 kg/mu, and the prevention and control effects of the microbial agents or inhibitors on crop pathogenic bacteria (tomato blight, peanut southern blight, potato scab) were detected at 120d, respectively.

The calculation mode of the prevention and control effect is specifically as follows:

(1) The classification standards of tomato wilt disease are as follows:

level 0: the plants are healthy, and no disease occurs; stage 1: the root base turns brown, the leaves are healthy, and the root has no obvious disease spots;

2 stages: the roots turn brown, and the leaves turn yellow; 3 stages: the root base brown and decays, the leaves yellow, and the root brown and blackens.

Disease index (%) was = Σ (number of patients at each stage x number of patients)/(total number of patients investigated x number of highest disease stage) ×100%.

Control effect (%) = (control disease index-treatment disease index)/control disease index x 100%.

(2) The classification standard of the peanut southern blight disease is as follows:

grade 0, asymptomatic; grade 1, only the basal stem produces disease; 2, the affected part accounts for less than 1/3 of the whole plant;

3, the affected part accounts for less than 2/3 of the whole plant; grade 4, plants approaching or having died.

(3) The classification standard of potato scab disease is as follows:

grade 0, no lesions; 1 grade, 1-2 scattered spots, and the area of the spots does not exceed 1/4 of the surface area of the potato skin;

2, 3-5 disease spots are arranged on the surface of the potato blocks, and the disease spots occupy 1/3-1/2 of the surface area of the potato skin;

and 3, the number of the disease spots is more than 10, and the area of the disease spots is larger than 1/2 of the surface area of the potato skin.

Disease index (%) was = Σ (number of tubers per disease grade x number of disease grade)/(number of total tubers investigated x number of highest disease grade) ×100%.

The test results are shown in Table 1.

From Table 1, the microbial agent prepared by utilizing Pseudomonas aeruginosa has good prevention and control effects on tomato fusarium wilt pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria. In particular, the microbial agent prepared from the bacterial powder obtained by spray drying of the pseudomonas aeruginosa fermentation broth can achieve 66.55% of prevention and control effects on tomato fusarium wilt pathogens, 72.03% of prevention and control effects on peanut southern blight pathogens and 61.58% of prevention and control effects on potato scab pathogens. Further, the microbial agent prepared from the pseudomonas aeruginosa fermentation broth can achieve 71.24% of prevention and control effects on tomato fusarium wilt pathogens, 74.37% of prevention and control effects on peanut southern blight pathogens and 63.21% of prevention and control effects on potato scab pathogens.

Further, according to the detection results of comparative examples 1 to 8 and examples 9 to 19, when the effective viable count of the microbial agent prepared by using the Pseudomonas aeruginosa fermentation broth is consistent with that of the microbial agent prepared by using the Pseudomonas aeruginosa fermentation broth for spray drying, the prevention and control effects of the microbial agent prepared by using the Pseudomonas aeruginosa fermentation broth on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria are obviously higher than those of the microbial agent prepared by using the Pseudomonas aeruginosa fermentation broth for spray drying. The bacterial strain is characterized in that the Pseudomonas aeruginosa fermentation broth contains metabolites of Pseudomonas aeruginosa besides bacteria per se, so that the prepared microbial agent has better prevention and control effects on tomato fusarium wilt pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria. In the microbial agent prepared from the bacterial powder subjected to spray drying treatment, various metabolites of the pseudomonas aeruginosa are lost in the process of spray drying by fermentation liquor, so that the effective components of the bacterial powder obtained by spray drying can be reduced, and the prevention and control effects of the microbial agent prepared from the pseudomonas aeruginosa fermentation liquor on tomato fusarium wilt pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria are higher than those of the microbial agent prepared from the bacterial powder.

As can be seen from the detection results of comparative example 5 and comparative examples 1 and 3, the prevention and control effects of the microbial agent of example 5 on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria are obviously higher than the prevention and control effects of the inhibitor of comparative example 1 comprising fermentation liquor and the inhibitor of comparative example 3 comprising carriers on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria, and are greater than the sum of the prevention and control effects of comparative example 1 and comparative example 3 on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria, so that the prevention and control effects of tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria can be further improved by the synergistic effect of the carrier and the pseudomonas viridis shown.

As can be seen from the detection results of comparative example 13 and comparative examples 2 and 3, the prevention and control effects of the microbial agent of example 13 on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria are obviously higher than the prevention and control effects of the inhibitor of comparative example 2 comprising bacterial powder and the inhibitor of comparative example 3 comprising carriers on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria, and are greater than the sum of the prevention and control effects of comparative example 2 and comparative example 3 on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria respectively, so that the prevention and control effects of the microbial agent of the present application on tomato blight pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria can be further improved through the synergistic effect of the carrier and the pseudomonas aeruginosa.

Examples 20 to 26

Examples 20-26 each provide a microbial agent. The above examples differ from example 1 in the type of carrier, and a microbial agent was prepared by mixing a Pseudomonas aeruginosa fermentation broth having a bacterial liquid concentration of 50 hundred million/ml with the carrier. The utilization is specifically shown in table 2.

Examples 27 to 34

Examples 27-34 each provide a microbial agent. The difference between the above examples and example 26 is the mixing ratio of humic acid powder and biochar in the carrier, and the microbial agent is prepared by mixing Pseudomonas aeruginosa fermentation broth with a bacterial liquid concentration of 50 hundred million/ml with the carrier. The utilization is specifically shown in table 2.

TABLE 2 microbial agents of examples 20-34

Performance test results two

The microbial agents provided in examples 20 to 34 were used as detection targets, and the detection targets were dried in a dark environment at 25℃to detect the effective bacterial content (plate colony count method) in the microbial agents at different times (0 d, 7d, 15d, 30d, 60d, 90d, 180 d), respectively.

As can be seen from Table 2, the effective viable count of the microbial agents of the present application under different time conditions is related to the type of carrier. When the effective viable count in the microbial agent is higher, the microbial agent has better prevention and control effects on crop pathogenic bacteria. When the effective viable count in the microbial agent is reduced, the prevention and control effect of the microbial agent on pathogenic bacteria of crops is also reduced. Therefore, it is necessary to ensure the effective viable count of the microbial agent as much as possible.

As shown by the detection results of comparative examples 22 to 25, when the carrier is diatomite, attapulgite powder, perlite or vermiculite, the initial content of the effective viable count in the prepared microbial agent is less than 6 hundred million/g, and the effective viable count in the microbial agent is lower and lower with the increase of time. Except that the effective viable count of the microbial agent with the diatomite as the carrier only remains 1.03 hundred million/g (less than 2 hundred million/g) at 180d, the effective viable count of the microbial agent with other types of microbial agents cannot be maintained to 180d, and even the effective viable count of the microbial agent with the vermiculite as the carrier cannot be detected at 60 d.

As is clear from the test results of comparative examples 20 and 21, the microbial agent with biochar as the carrier had an effective viable count of 7.76 hundred million/g at 0d and 2.21 hundred million/g at 180 d; the effective viable count of the microbial agent with the humic acid powder as the carrier is 6.68 hundred million/g (less than 7.76 hundred million/g) at 0d, and 3.08 hundred million/g (more than 2.21 hundred million/g) at 180 d. Obviously, the microbial agent with the carrier being the biochar has higher effective viable count at 0-15d, lower effective viable count at 30-180d, and the microbial agent with the carrier being the humic acid powder has lower effective viable count at 0-15d, and higher effective viable count at 30-180 d. However, the effective viable count of the microbial agent is directly related to the prevention and control effect of the microbial agent on pathogenic bacteria of crops. As can be seen from the detection results of example 26, the effective viable count of the microbial agent prepared when the carrier is a mixture of biochar and humic acid powder is greater than that of the microbial agent prepared when the carrier of example 21 is humic acid powder in 0-30d, and greater than or close to that of the microbial agent prepared when the carrier of example 20 is biochar in 60-180 d.

Therefore, in order to ensure that the prepared microbial agent can keep a higher effective viable count, the mixture of humic acid powder and biochar is selected as a carrier of the microbial agent.

In addition, as is clear from the results of comparative examples 26 to 34, the mixing ratio of humic acid powder and biochar was controlled to be (0.5 to 4): 1, the effective viable count of the prepared microbial agent is more than 2.8 hundred million/g at 180 d; when the mixing proportion of humic acid powder and biochar is controlled to be (1-2): 1, the effective viable count of the prepared microbial agent is more than 3 hundred million/g at 180 d. Therefore, in order to simultaneously achieve both economic benefit and prevention and control effect, the mixing ratio of humic acid powder and biochar is preferably controlled to be (1-2): 1.

Example 27

In the embodiment, the preparation method of the bacterial powder in the microbial agent is optimized, and the obtained effective viable count and the obtained dry matter yield are detected. The parameters examined are air inlet temperature, feeding flow and atomization pressure in the process of preparing the bacterial powder. The results of the measurements are shown in Table 3 and FIGS. 1-5.

TABLE 3 optimization procedure for the preparation of Pseudomonas aeruginosa powder

The method for detecting the effective viable bacteria number comprises the following steps: plate colony counting method.

The dry matter yield was calculated as follows: weight after spray drying/weight before spray drying x 100%.

As shown by the detection results in Table 3, in the preparation method of the bacterial powder, the air inlet temperature of spray drying is controlled at 140-190 ℃, the feeding flow is controlled at 200-600L/h, the atomization pressure is controlled at 0.1-0.5Mpa, and the bacterial powder has high effective viable count and good dry matter yield.

As can be seen from the comparison of the results of FIGS. 1-2 and the results of the numbers 1-6, the effective viable count in the obtained bacterial powder continuously decreases with the increase of the inlet air temperature, but the dry matter yield of the bacterial powder continuously increases. In consideration of the fact that the bacterial powder has high effective viable count and dry matter yield to the greatest extent, the air inlet temperature of spray drying is preferably controlled at 170 ℃ in the preparation process of the bacterial powder.

As can be seen from the comparison of the results of figures 3-4, number 4 and number 7-10, the effective viable count in the obtained bacterial powder slowly increases with the increase of the feeding flow, but the dry matter yield of the bacterial powder tends to increase firstly and then decrease. In consideration of the fact that the bacterial powder has high effective viable count and dry matter yield to the greatest extent, the feeding flow rate of spray drying is preferably controlled at 400L/h in the preparation process of the bacterial powder.

As can be seen from the comparison of the results of FIG. 5, no. 4 and No. 11-14, the effective viable count in the obtained bacterial powder shows a tendency of rising and then falling along with the rising of the atomization pressure, and the dry matter yield of the bacterial powder reaches 98% when the atomization pressure is 0.1Mpa. In consideration of the fact that the bacterial powder has high effective viable count and dry matter yield to the greatest extent, the atomization pressure of spray drying is preferably controlled to be 0.1Mpa in the preparation process of the bacterial powder.

According to the above, in the preparation process of the bacterial powder, the air inlet temperature is set to 170 ℃, the feeding flow is set to 400L/h, the atomization pressure is set to 0.1Mpa, and the prepared bacterial powder has higher effective viable count and better dry matter yield.

Performance test results three

The preparation method of the microbial agent provided in the example 1 and the preparation method of the microbial agent provided in the example 9 are respectively used for preparing the microbial agent with effective bacterial content shown in the table 4, and the microbial agent is added into continuous cropping agricultural fields according to the corresponding application amount in the table, and the prevention and control effects of the microbial agent on crop pathogenic bacteria are detected under 120d respectively. The test results are shown in Table 3.

TABLE 4 method for controlling pathogenic bacteria of crops using microbial agent

As shown in Table 4, when the effective viable count of the microbial agent prepared by utilizing the Pseudomonas aeruginosa fermentation broth is 0.85-2.5 hundred million/g, the microbial agent can achieve 71.23% of the control effect on tomato blight pathogenic bacteria, 74.36% of the control effect on peanut southern blight pathogenic bacteria and 63.2% of the control effect on potato scab pathogenic bacteria when the application amount is controlled to be 40-120 kg/mu. Considering both economic benefit and prevention and control effect, the microbial agent with the effective viable count of 1.25-2.5 hundred million/g can be selected and utilized, and the application amount of the microbial agent is controlled to be 40-80 kg/mu.

When the effective viable count in the microbial agent prepared from the bacterial powder obtained by spray drying of the pseudomonas aeruginosa fermentation broth is 2.5-5 hundred million/g, the microbial agent can achieve 59.58% of prevention and control effects on tomato blight pathogenic bacteria, 63.98% of prevention and control effects on peanut southern blight pathogenic bacteria and 55.42% of prevention and control effects on potato scab pathogenic bacteria when the application amount is controlled to be 40-80 kg/mu.

From the above, compared with the microbial agent prepared by the fungus powder obtained by spray drying the pseudomonas aeruginosa fermentation broth, the microbial agent prepared by the pseudomonas aeruginosa fermentation broth has better prevention and control effects on tomato fusarium wilt pathogenic bacteria, peanut southern blight pathogenic bacteria and potato scab pathogenic bacteria.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting thereof; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.

Claims

1. The microbial agent is characterized by comprising a carrier and pseudomonas aeruginosa with the preservation number of CGMCC No.28235 loaded on the carrier.

2. The microbial agent of claim 1, wherein the microbial agent is prepared using a fermentation broth of pseudomonas aeruginosa and the carrier;

optionally, the effective viable count of the pseudomonas aeruginosa in the microbial agent is 0.2-5 hundred million/g;

3. The microbial agent according to claim 1, wherein the microbial agent is prepared by using the powder of pseudomonas aeruginosa after spray drying and the carrier;

optionally, the effective viable count of the pseudomonas aeruginosa in the microbial agent is 0.2-20 hundred million/g;

optionally, the effective viable count of the pseudomonas aeruginosa in the microbial agent is 5-10 hundred million/g;

4. The microbial agent according to claim 1, wherein the carrier is selected from any one or more of humic acid powder, diatomaceous earth, biochar, attapulgite powder, perlite and vermiculite;

optionally, the carrier comprises the humic acid powder and the biochar.

5. The microbial agent according to claim 4, wherein the weight ratio of the humic acid powder to the biochar in the carrier is (0.2-5): 1.

6. the microbial agent of claim 1, wherein the carrier has a particle size of 120-250 μm.

7. A method for preparing a microbial agent according to any one of claims 1 to 6, characterized in that the method comprises the following steps: uniformly mixing the dried and sterilized carrier with pseudomonas aeruginosa with the preservation number of CGMCC No.28235 to obtain a microbial agent;

8. Use of a microbial agent according to any one of claims 1-6 in the field of improving and controlling crop diseases.

9. Use of a microbial agent according to any one of claims 1-6 for improving and controlling peanut southern blight, tomato blight and potato scab.

10. A method for controlling crop pathogens, characterized in that the microbial agent of any one of claims 1-6 is applied to a farmland in need of controlling crop pathogens;

optionally, the microbial agent is prepared by utilizing the fermentation liquor of the pseudomonas aeruginosa, and when the effective viable count is 0.85-2.5 hundred million/g, the application amount of the microbial agent is 40-120 kg/mu;