Microbial Transformation Of The Insecticide Imidacloprid,

Biotransformation and biocatalysis technology has the character of high efficiency, diversity, specialty of substrate, regioselectivity, chemical selectivity, enantiomorph selectivity. So it is praised with "the third wave of biotechnology" as followed medicine biotechnology and agriculture biotechnology. In this paper, we used microbial transformation method to develop the process for creation of new pesticide. The neonicotinoid insecticide imidacloprid (IMI) which has outstanding biological efficacy, low toxicity to warm-blooded animals was selected as biotransformation substrate. We had isolated and screened microorganisms with the ability of transforming IMI from soils and stock cultures. We obtained the hydroxylated product 5-hydroxy IMI produced by using resting cell transformation of IMI, then 5-hydroxy IMI was further hydrolyzed under acid and heating conditions to produce olefin IMI which has higher biological efficacy than IMI.Through enrichment culture using IMI as sole nitrogen source, seven strains of bacteria from soils showed the ability of transformation of IMI to a more polar compound. Among them, NJ1 strain from soil exhibited higher IMI transformation activity. This strain was identified as Stenotrophomonas maltophilia on the basis of the physiological tests with ATB Expression system (ID32 STREP) (bioMerieux Vitek) and partial 16s ribosome RNA gene sequence. Meanwhile, we selected some bacteria, yeasts and fungi strains from stock cultures in our lab for examination of their IMI transformation activity. The result showed some microorganisms involved bacteria and fungi also had the ability of transformation IMI. Among them, S. maltophilia CGMCC 1.1788 showed the highest activity of transformation IMI, which was higher than that of S. maltophilia NJ1 strain. Thus S. maltophilia CGMCC 1.1788 was chosen for further study.The effects of cultivation temperature, cultivation time and inducer on the IMI transformation activity by S. maltophilia CGMCC 1.1788 strain were examined. When cultivation temperature changed from 20 ℃ to 35℃,the total transformation activity of...