Genetic and Phenotypic Diversity of Parathion-Degrading Bacteria Isolatedfrom Rice Paddy Soils

摘要

Three parathion-degrading bacteria and eight pairs ofbacteria showing syntrophic metabolism of parathionwere isolated from rice field soils, and their genetic andphenotypic characteristics were investigated. The threeisolates and eight syntrophic pairs were able to utilizeparathion as a sole source of carbon and energy, producingp-nitrophenol as the intermediate metabolite during thecomplete degradation of parathion. Analysis of the 16SrRNA gene sequence indicated that the isolates wererelated to members of the genera Burkholderia, Arthrobacter,Pseudomonas, Variovorax, and Ensile,: The chromosomalDNA patterns of the isolates obtained by polymerase-chain-reaction (PCR) amplification of repetitive extragenicpalindromic (REP) sequences were distinct from one another.Ten of the isolates had plasmids. All of the isolates andsyntrophic pairs were able to degrade parathion-relatedcompounds such as EPN, p-nitrophenol, fenitrothion, andmethyl parathion. When analyzed with PCR amplificationand dot-blotting hybridization using various primerstargeted for the organophosphorus pesticide hydrolasegenes of previously reported isolates, most of the isolatesdid not show positive signals, suggesting that their parathionhydrolase genes had no significant sequence homologywith those of the previously reported organosphophatepesticide-degrading isolates.