Biodegradation of PCB congeners by Paraburkholderia xenovorans LB400 in presence and absence of sediment during lab bioreactor experiments

Hydroxylated Polychlorinated Biphenyls Are Emerging Legacy Pollutants in Contaminated Sediments

“…OH-PCBs may be transformed to methoxylated polychlorinated biphenyls . PCBs can be aerobically oxidized with dioxygenase enzymes in the biphenyl upper pathway to catechol metabolites which can spontaneously be cleaved and transform to chlorobenzoate or can rearrange to orthoquinone metabolites. − PCBs can also be anaerobically dechlorinated by becoming terminal electron acceptors in the respiration chains. ,, The microbial communities in the brackish of NBH and in the freshwater of AWL are different and may alter OH-PCB and PCB levels differently. We could not evaluate the correlation between OH-PCB and PCB levels in IHSC because we have only two samples.…”

“…In both scenarios, environmental conditions and the age of sediments due to the original contamination would affect the accumulation of OH-PCBs in the sediment. The microbial communities are likely to be different between the two sites, thus resulting in the differences in the specificities to PCB precursors and OH-PCB products and in conversion rates. , Also, the difference in the pH, salinity, and flow of the water as well as the compositions of sediments would result in different accumulation of OH-PCBs in the two sediments. Accordingly, the OH-PCB signals of AWL and IHSC sediments can be partly similar but different from those in A1248.…”

Aerobic Bioaugmentation to Decrease Polychlorinated Biphenyl (PCB) Emissions from Contaminated Sediments to Air

“…Paraburkholderia xenovorans strain LB400, isolated from PCB-contaminated landfill soil in 1985 − and widely regarded as an efficient bph pathway utilizer, − is the bioaugmentation strain used here. Our previous work reproduced the results of these early PCB biodegradation assays using modern analytical instrumentation and showed how LB400 preferentially biodegraded bioavailable LC-PCBs but struggled to biodegrade LC-PCBs bound to sediment particles gathered from a contaminated site. − That experiment was designed to demonstrate that limited mass transfer (low bioavailability) is a key constraint to effective PCB biodegradation and to document LB400′s broad congener specificity. − Compounds present in plant rhizospheres can act as biosurfactants to make PCBs and other hydrophobic organic compounds tightly bound to organic matter more bioavailable for microbial transformation . For example, the phytogenic biosurfactant, saponin, can aid aerobic PCB-contaminated sediment remediation. , Combined anaerobic–aerobic bioaugmentation by use of bioamended activated carbon is a promising alternative for stimulating PCB biodegradation processes in situ. − However, bioaugmentation strategies for mitigating airborne PCB emissions using aerobic PCB-degrading microorganisms have not been documented.…”

“…Sediment was collected from a decommissioned, PCB-contaminated emergency overflow lagoon located in Altavista, VA (Figure S1). Information on sediment properties (Table S1), homogenization method, and sediment sampling strategy have been previously described . The average total PCB concentration (∑PCB = sum of 171 congeners) was 6350 ng/g (STD = 312 ng/g, n = 6).…”

“…(A) PCB congener profile of Altavista sediment (previously determined) . For ease of reference, a condensed profile of individual PCB congeners is shown along the horizontal axis although all 209 congeners (minus surrogate and internal standards) were measured.…”