Method for screening mixed bacterium degradation microbial inoculum taking chlorimuron-ethyl as substrate

Abstract

The invention relates to the technical field of biodegrading pesticide residue, in particular to a method for screening a mixed bacterium degradation microbial inoculum taking chlorimuron-ethyl as a substrate. The method comprises the following steps of: adding the chlorimuron-ethyl at the concentration of 100mg / L into a 1 / 5LB culture medium, and inoculating the bacterial suspension which accounts for 5 to 10 volume percent of the culture medium; performing shake cultivation on the bacterial suspension at the temperature of between 28 and 30 DEG C and at a speed of 50 to 180 r / min for 5 to 7 days, and inoculating nutrient solution which accounts for 5 to 10 volume percent of the culture medium into the novel 1 / 5LB culture medium, wherein the concentration of the chlorimuron-ethyl is increased progressively in a ratio of 100mg / L, and after inoculating for 5 times, the concentration of the chlorimuron-ethyl in the culture medium is 500mg / L; and then inoculating the nutrient solution which accounts for 5 to 10 volume percent of the culture medium for 5 times to obtain the mixed bacterium strain, wherein the adding concentration of the chlorimuron-ethyl is always 500mg / L. The degradation rate reaches over 70 percent after the mixed bacterium strain is detected by a liquid chromatography. The mixed bacterium degradation microbial inoculum taking the chlorimuron-ethyl as the substrate is obtained by performing fermentation and expanding culture on the bacterium strain.

Description

technical field [0001] The invention relates to the technical field of biodegradation of pesticide residues, in particular to a screening method for a mixed-bacteria degradation bacterial agent using chlorimuron-methyl as a substrate. technical background [0002] Chlorimuron-methyl is a broad-spectrum and broad-effective herbicide for soybean fields. It has been used in my country since the early 1990s. The effective amount per hectare is only 15-22.5 grams. It is easy to use, low in cost, and has a very wide application area. The area is about 9 million hectares, and the area used by chlorimuron-methyl is more than 2.5 million hectares, nearly 1 / 3. In Heilongjiang Province alone, the annual consumption of chlorimsulfuron-methyl in soybean fields exceeds 400 tons, covering 1.33 million hectares. But because chlorimuron-methyl is not easy to volatilize, not easy to photolyze, and the residual period is very long, it is easy to cause phytotoxicity to the sensitive crops after...

AI Technical Summary

Problems solved by technology

[0003] At present, many experts at home and abroad have taken a series of measures to reduce the harm caused by chlorimsulfuron residues, mainly including adding compound agents to reduce the dosage of chlorimsulfuron-methyl, developing drug-resistant transgenic crops, and developing chemical antidotes, etc. These measures cannot fundamentally solve the problem of pesticide residues

There are many precedents for the development of microbial agents to eliminate pesticide residue pollution at home and abroad, and there are many successful cases, such as organophosphorus pesticides, pyrethroid pesticides, carbamate pesticides, etc., but the isolated single-bacteria agent Low activity, high possibility of degradation and rejection in the environment, unstable activity, limiting applications

Sulfonylurea herbicides are relatively difficult to degrade. At present, there are few bacterial agents in this area, but research has found that microbial degradation is also a major degradation pathway for this type of pesticide. Due to the complex structure and difficult degradation, the mixed bacterial agent should be considered It is a feasible direction for biodegradable pesticides