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Abstract: New bacterial strains capable of degrading polychlorinated biphenyls (PCBs) were isolated from soil contaminated with waste from dye industry. The enriched colonies were exposed to 2,3-dihydroxybiphenyl (2,3-DHBP) and produced yellow metabolite of biphenyl catabolic pathway. Based on their morphological, chemotaxonomic characteristics and 16S rRNA phylogenetic typing, the strains were identified as Stenotrophomonas sp. JSG1 and Cupriavidus taiwanensis JSG2. They are able to utilize ortho- and para-substituted mono-, di-, and trichlorinated biphenyls (4-Chlorobiphenyl, 4,4’-Chlorobiphenyl and 2,4’,5-Chlorobiphenyl respectively) as sole carbon and energy sources. The presence of 2,3-Dihydroxy biphenyl dioxygenase (2,3-DHBD) was confirmed on crude protein extract of PCB degraders and their molecular weight is about 36 kDa. GC analysis revealed that both organisms possess significant PCB degrading activity. The active metabolic rate of the strains were identified by the production of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) and their level estimated at a range of time points. Investigations into the genetic systems controlling the degradation of polychlorinated biphenyl on these organisms and their co-metabolic study are in progress.


Keyword: HOPDA, Polychlorinated biphenyl, 2, 3-Biphenyl dioxygenase, 2,3-DHBP