Some dehalorespiring bacteria reductively decholorize one or more chlorine atoms of polychlorinated compounds to form the congeners with lower chlorine atoms and less toxic which are enable to be mineralized completely by aerobic bacteria. In the herbicide/dioxin bioremediated cells of former Bien Hoa military airbase, the presence of many dehalorespiring bacterial groups were detected by nested-PCR method using pairs of 16S rRNA gene-specific primers. These bacteria included sulfate reducing bacteria of subgroups such as Desulfovibrio-Desulfomicrobium, Desulfococcus-Desulfosarcina-Desulfonema)
Desulfitobacterium (facultative dehalorespirers) and Dehalococcoides (obligate dehalorespirers). The obtained results demonstrated that dehalorespiring bacteria detected by nested-PCR method are diverse. However
two groups of potential obligated dehalorespiring bacteria such as Dehalobacter and Dehalogenimonas were not able to detect by this method. By HPLC analysis, reductive dechlorization of 2,4,5- T was identified in enrichment samples of dehalorespiring bacteria after 12 weeks of culture. Proposed intermediate products were 2,4,5- TCP and another unidentified compound. The obtained results confirmed the role of dehalorespiring bacteria in detoxification of herb icidesldi ox in contaminated soils by bioremediation.