CHARACTERISATION OF GEN FRAGMENTS ENCODED HERBICIDE METABOLIZING ENZYMES FROM THREE DIBENZOFURAN-DEGRADING BACTERIA

Abstract

2,4-D and 2,4,5-T herbicide-degrading bacteria were found in several bacterial genera. Many of these bacteria were also detected in soil that collected from three regions of Vietnam including herbicide/dioxin contaminated "hot spot" in US fonner military base at Danang airport. The tfdA, tfdAa and cadA-like gene fragments were isolated in 2,4-D and 2,4,5-T degrading bacteria and also in total DNA samples that were directly extracted from soils in Danang "hot spot". However, there is no study on transfer of those genes within soil bacteria community. In this report, the tfdA and cadA-like gene fragments were detected in three dibenzofuran-degrading bacteria Rhodococcus sp. HDN3, Paenibacillus sp. A03 and Terrabacter sp. DMA that were isolated from soil and sediment in this site. The sequence analysis of tfdA gene fragments from both bacterial strains Ao3 and DMA revealed that they had 98% similarity to tfdA sequence in plasmid pJP4 of Ralstonia eutropha JMP134 and also a high homology level to those genes from 2,4-D degrading bacteria as well as from total soil DNA isolated from soil samples in Vietnam. In another hand, tfdA gene fragment in HDN3 strain showed 99% homology to those gene fragments in 2,4-D utilizing bacteria such as Burkholderia sp. RASC and Burkholderia sp. Ff54. cadA-like gene fragments in both bacterial strains Ao3 and DMA showed 99 and 86% similarity respectively. to this cadA-like gene in HS07 clone originated from activated sludge that was admented 2,4-D