engleski

PCB degrading bacteria from marine sediments

The objective of this work was to study the catabolic potential of marine sediment bacteria in PCB degradation. Bacterial communities were isolated from different marine sediments collected at urban areas along the Croatian Adriatic coast (vicinity of Rijeka, Zadar and Dubrovnik). A microcosm enrichment approach was employed to isolate bacterial communities with the capability to use biphenyl as the sole carbon and energy source. Enrichment experiments were performed in sea water diluted with mineral salts medium (SM medium) and supplemented with biphenyl. The PCB degradation activity of enriched biphenyl-degrading communities was screened in batch culture experiments using SM medium and commercial PCB mixture (PCB 50) containing 50% chlorine and congeners with two- to heptachlorobiphenyl. More detailed characterization of the isolated bacteria and the study of their catabolic activity in the transformation of PCBs were performed with Aroclor 1248 and individual PCB congeners. Microcosm experiments resulted in the enrichment of eight communities containing one to two members that were able to grow on biphenyl as the only carbon source. Those members, expressing 2, 3- dihydroxybiphenyl dioxygenase activity were identified as species belonging to the genus Rhodococcus and Sphingomonas (by using 16S rDNA gene sequence comparison). Five out of eight enrichedenriched biphenyl-degrading communities also showed PCB transformation activity. GC/MS analyses during biodegradation experiments with Aroclor 1248 and individual PCB congeners suggested that all isolates obtained from enriched communities preferred transformation of lower chlorinated congeners (di- to tetrachlorobiphenyls) and were slightly different in their PCB transformation capabilities

PCB; biodegradation; marine sediments

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