Genetics of the carbofuran-degrading bacterium CFO6

Carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl N-methylcarbamate) is extensively used as a soil-incorporated N-methylcarbamate insecticide to control a variety of insect pests that infest crops such as corn, potatoes, rice, and strawberries. Because of its high mammalian toxicity and high mobility, it is considered to be a potential environmental pollutant and it has been detected in groundwater in widely diverse environments such as Washington state and Florida. A greater understanding of carbofuran biodegradation by microorganisms, and how these microorganisms acquire the ability to degrade the insecticide, is required for developing strategies to prevent groundwater contamination by carbofuran.; This study was conducted to analyze the biodegradation of carbofuran, to determine distribution of carbofuran-degrading microorganisms throughout two soil profiles with different histories of exposure to carbofuran, and to study the genetics of a carbofuran-degrading bacterium CF06.; Mineralization of {dollar}lbracksp{lcub}14{rcub}{dollar}-carbonyl) carbofuran was faster and to a greater extent than that of {dollar}lbracksp{lcub}14{rcub}{dollar}C-URL) carbofuran. Enhanced biodegradation of carbofuran was observed in soil with preexposure to carbofuran throughout the soil profiles. Mineralization of carbofuran at different soil depths were different, with surface soils exhibiting higher mineralization rate than subsurface soils. Populations of carbofuran-degrading microorganisms varied with different soils and different soil depths.; A bacterial strain (CF06) that can mineralize both the carbonyl group and the aromatic ring of carbofuran, and utilize carbofuran as sole carbon and nitrogen source, has been isolated from soil. Phospholipid fatty acid analysis (PLFA) and 16S rRNA sequencing analysis has placed CF06 in the alpha group of Proteobacteria, specifically Sphingomonas sp. CF06 contains five plasmids, at least some of which are required for metabolism of carbofuran. Of the five plasmids, four contain large regions of overlap, and these plasmids are unusually rich in insertion sequence (IS) elements. Six different IS elements have been cloned from CF06. One of these IS elements, designated IS1412, has been completely sequenced and shares significant homology with three previously described IS elements found in other alpha Proteobacteria.