The Effect Of Carbendazim, Furadan On Microbes And Soil-enzyme Activities Of Hunan Red Soil And Isolation, Identification, Degradation Characteristics Of Carbendazim-degrading Bacteria

With the fast development of industry and agriculture of our country, a large number of pesticides, heavy metals have released to environment, which polluted soil and did harm to people's health. The factors that any harm soil health and cause soil function deterioration should be forecasted and warning. Therefore, in order to protect soil biological diversity, remedy damaged soil and carry out soil continuable utilization, it has very important sense to make clear the biological effects of pesticides and heavy metals on soil pollution, put forward biological warning index of soil pollution, constitute biological warning system of soil safe.The experiment took Chinese southern type soil-Qiyang (Hunan province) red soil as experimental object and systematically researched the effects of bactericide carbendazim and insecticide carbofuran on soil microorganism and four soil enzymes. The research isolated and screened a strain of carbendazim-degrading bacterial strain 1-1, whose biological characteristics and carbendazim degradation were also researched. The main results of the experiment are as follows.1. After bactericide carbendazim was applied to soil, the results are compared with control soil (without carbendazim): The number of soil aerobic microorganism and all kinds of physiological microorganisms were markedly changed. In the soil whose concentration is over 50 mg/kg dried soil carbendazim, on the seventh day, the number of soil mold nitrifying bacteria was restrained over 50%, bio-chemistry activity of urease and phosphatase was restrained over 25%. The number of soil mold, nitrifying bacteria and bio-chemistry activity of urease and phosphatase can sensitively reflect early pollution of carbendazim in Hunan red soil. According to the results of the experiment, urease activity can be as the warning index of carbendazim pollution of Hunan red soil, whose threshold value of warning is about 83.52mg/kg dried soil.2. After insecticide carbofuran was applied to soil, the results were compared with control soil (without carbofuran): The number of soil aerobic bacteria actinomyces, ammonifying bacteria and mold was strongly restrained, and the restrainratio and pesticide concentration have positive correlation. The number of soil ammonifying bacteria actinomyces and mold, bio-chemistry activity of urease can sensitively reflect early pollution of carbofuran in Hunan red soil. So they can be as biological index of carbofuran pollution. Actinomyces can be as warning index of carbofuran pollution and the warning threshold value is 10mg/kg dried soil within 7 days.3. A bacterial strain 1-1 capable of utilizing carbendazim as the sole carbon and energy sources was isolated from carbendazim-treated Hunan red soil, which was identified as P- proteobacteria; Ralstonia sp. based on the results of phenotypic features, G+C and phylogenetic analysis of 16S rDNA sequences. Yeast extract could accelerate the degradation of carbendazim by strain 1-1, the degradation rate was 95.56% in the carbendazim (500mg/L)-mineral medium supplemented with yeast extract (150mg/L) within 24d.The results of the research opened up the effects of carbendazim and carbofuran pollution on microorganism and enzyme activities of Qiyang (Hunan province) red soil, and firstly point out warning index and the warning threshold value of microorganism and enzymes of the pollution of carbendazim and carbofuran. This research also put forward parameter and basic theoretic datum for constituting soil safe biological warning system and provide the basis and specific index for country constituting the standard of soil environment quality in the future. The isolated carbendazim-degradating bacterium offered new microorganism resouce for researching the pathway of carbendazim biodegradation and the bioremediation of carbendazim pollution.