Study On The Microbial Agents Of Carbendazim-Degrading Strain Djl-6 And Acetamiprid-degrading Strain D-2

At present,the level of pesticide use technology in China is low,which leads to an increase in the input of pesticides.Carbendazim and acetamiprid are widely used in facility agriculture because of their low toxicity and high efficiency.With the expansion of the planting area,the residual problems in the soil of carbendazim and acetamiprid have become increasingly prominent,posing a potential risk to the ecological environment.The application of microorganisms to repair pesticide residue pollution is recognized as a safe,inexpensive,efficient method with great potential and application value.At present,the research on remediation of pesticide residues is mostly the isolation and screening of highly degrading microorganisms of pesticide contaminants and their degradation mechanism.There are few studies on the preservation conditions of microbial agents.The preservation of microbial agents hinders the large-scale production and application of degrading microbial agents.Therefore,the Carbendazim-degrading strain Rhodococcus qingshengii sp.nov.djl-6 and the Acetamiprid-degrading strain Pigmentiphaga sp.D-2 isolated and screened from the soil in the laboratory were used as test strains to study the different preservative formulations of the degrading bacterium and the preliminary preparation of the microbial agents.It provides some basis for the preservation and application of degrading bacteria agent.The main research contents and results are summarized as follows:1.Degradation of pesticides by carbendazim-degrading strain djl-6 and acetamiprid-degrading strain D-2 and their colonization ability in roots of green vegetables.The degradation effect of strain djl-6 on carbendazim and the degradation effect of strain D-2 on acetamiprid were determined.The strain djl-6 was able to completely degrade carbendazim at a concentration of 50 mg/kg in inorganic salt medium at 72 h.The strain D2 was able to completely degrade acetamiprid at a concentration of 50 mg/kg in the inorganic salt medium at 72 h.Strain djl-6 and strain D-2 were labeled by GFP.The seedlings of green vegetables were immersed in the suspension of labeled strain djl-6 and strain D-2 for 3 days.The colonization of the strain with GFP marker gene on the root surface of green vegetables was observed by laser confocal microscopy(CLSM).The results showed that both strains of degrading bacteria could colonize in the roots of green vegetables.2.Study of liquid bacterial agents for carbendazim-degrading strain djl-6 and acetamiprid-degrading strain D-2.Increase the number of viable bacteria in the microbial agent by adding preservatives and protective agents.The number of viable bacterium and the degradation rate of the degrading bacterium liquid microbial agent are increased by adding a protective agent.The strain of djl-6 with 0.30%sodium citrate,0.30%carboxymethyl cellulose and 0.20%CaCl2 as a protective agent can increase the number of viable bacterium in the liquid bacterium by 32.03%,the viable bacterium count of the strain D-2 with 0.20%dextrin,0.20%sodium citrate and 0.30%CaCl2 as a protective agent was increased by 38.70%.The soil pesticide residue degradation experiment was carried out by pesticide pots.After 30 days of storage of the bacterium of the two strains,the djl-6 strain could degrade carbendazim at a concentration of 5 mg/kg in soil within 10 days.The D-2 strain can degrade acetamiprid at a concentration of 10 mg/kg in soil within 10 days.The research showed that the addition of preservatives and protective agents could increase the viable count and degradation of strain djl-6 and strain D-2.3.Study of bacterial manure for carbendazim-degrading strain djl-6 and acetamiprid-degrading strain D-2.Select earthworm manure,pig manure,chicken manure,straw fertilizer,rice bran,peat and peanut shell powder as carriers,inoculate two strains of degrading bacteria,and make the degrading bacteria into bacterial fertilizer.When stored for 120 days,except for contaminated rice bran fertilizer,the number of viable bacteria in all other bacterial fertilizers was more than 107 cfu/g.When stored for 120 days,djl-6 was used as the bacteria-fertilizing bacteria for inoculating microorganisms.The largest number is the manure carrier fertilizer,and the number of viable cells is 7.01×108 cfu/g.The lumber of live bacteria with D-2 as the inoculated microorganism was the largest in pig manure,and the number of viable cells was 4.33×108 cfu/g.Then the effect of bacterial fertilizer degradation was studied by pot experiment.The djl-6 as the inoculated microbial manure could degrade 94.3%of carbendazim at a concentration of 5 mg/kg within 10 days after storage for 30 days.The D2 as a microbial inoculated manure,after 30 days of storage,it was able to degrade 95.5%of acetamiprid at a concentration of 10 mg/kg within 10 days.Finally,the colonization dynamics of strain djl-6 and strain D-2 in the rhizosphere soil of green vegetables were tested.The research showed that the viable count of bacteria could be maintained at 108 cfu/g for 120 days when earthworm manure was selected as inoculation vector,and inoculate the soil with the final concentration of 108 cfu/g dry soil djl-6 and strain by root irrigation.The D-2 could maintain at least 12 days in the rhizosphere soil of green vegetables.Adding earthworm manure can increase the number of colonies of djl-6 and D-2.