Preparation And Application Of Deltamethrin Degrading Bacteria Agent

Pyrethroid is a kind of artificial biomimetic compounds which mimic natural pyrethrin,and one of the main agricultural insecticides in recent years.At present,the common used pyrethroid pesticides include deltamethrin,cyhalothrin,cypermethrin and bifenthrin.Deltamethrin is one of the fastest-growing amount of pyrethroid insecticides,and is the highest virulence of them.The residue of this kind of insecticides has become one of the most dominant insecticide ones in farm produce.The bioremediation has become one of the hot spots of researches all over the world,and the products of microbial agents for degrading pesticides have been developed in foreign countries.In this dissertation,taking deltamethrin as a model pollutant,degrading-bacteria enrichment and isolation,biodegradation characteristics of the bacteria and preparation and application of degrading-bacteria agents were studied systematically.The results were summarized as follows:1.A new efficient deltamethrin-degrading bacteria XQ08 was isolated and identified.The strain XQ08 was isolated from the long-term pesticide-contaminated soil,and the 5 d degradation rate of the deltamethrin's concentration of 50 mg/L reached 66.76%.Based on the morphological,physiological and biochemical characterization,and phylogenetic analysis of the 16 S rDNA gene sequence,XQ08 was identified as Stenotrophomonas maltophilia.2.Degradation characteristics of strain XQ08 were studied in several conditions.The effects of different culture temperatures,different pH,different concentrations of deltamethrin,different inoculation quantities and the effect of different concentrations of adding carbon source on the biodegradation ability of the bacterium stain were studied respectively.The results showed that the stain XQ08 had the highest degradation rate of deltamethrin when the temperature of 35?(5 d degradation rate was 68.33%),pH = 8(5 d degradation rate was 66.84%),the concentration of bacteria OD600=1.0(5 d degradation rate was 67.69),pesticide concentration of 1mg / L(5 d degradation rate was 72.02%),adding 2% glucose(5 d degradation rate was 71.93%).It was also found that strain XQ08 had ability of degradating chlorpyrifos,imidacloprid and pyrethroid pesticides,chlorine cyhalothrin,cypermethrin,and the 5 days of degradation rate of them reached 20.89% and 25.54% and 33.30% and 35.47% respectively.3.The fermentation conditions of the degradation bacterium were optimized by single factor analysis.When the pH was 8,the carbon source was 1% maltose,the nitrogen source was 0.5% ammonium chloride,the temperature was 35?,and the inoculation amount was 1%,the strain XQ08 grow fastest.Liquid degrading bacteria agent was prepared and practical degradating effect was studied in the field and pot experiment.The results showed that: while applying of bacteria agents 2 days after the spray of pesticides with concentration of 40 L/hm2,5 d indoor potted degradation rate was 82.35%,and field degradation rate was 78.07%.The strain XQ08 can effectively reduce the deltamethrin residue of plant.