We conducted experiments to determine whether bioaugmentation with aerobic, polychlorinated biphenyl (PCB)-degrading microorganisms can mitigate polychlorinated biphenyl (PCB) emissions from contaminated sediment to air. Paraburkholderia xenovorans strain LB400 was added to bioreactors containing PCB-contaminated site sediment. PCB mass in both the headspace and aqueous bioreactor compartments was measured using passive samplers over 35 days. Time-series measurements of all 209 PCB congeners revealed a 57% decrease in total PCB mass accumulated in the vapor phase of bioaugmented treatments relative to non-bioaugmented controls, on average. A comparative congener-specific analysis revealed preferential biodegradation of lower-chlorinated PCBs (LC-PCBs) by LB400. Release of the most abundant congener (PCB 4 [2,2′-dichlorobiphenyl]) decreased by over 90%. Simulations with a PCB reactive transport model closely aligned with experimental observations. We also evaluated the effect of the phytogenic biosurfactant, saponin, on PCB bioavailability and biodegradation by LB400. Time-series qPCR measurements of biphenyl dioxygenase (bphA) genes showed that saponin better maintained bphA abundance, compared to the saponin-free treatment. These findings indicate that an active population of bioaugmented, aerobic PCB-degrading microorganisms can effectively lower PCB emissions and may therefore contribute to minimizing PCB inhalation exposure in communities surrounding PCB-contaminated sites.

中文翻译：

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有氧生物强化可减少受污染沉积物向空气中的多氯联苯 (PCB) 排放


我们进行了实验，以确定用需氧多氯联苯 (PCB) 降解微生物进行生物强化是否可以减少受污染沉积物向空气中排放的多氯联苯 (PCB)。将Paraburkholderia xenovorans菌株 LB400 添加到含有 PCB 污染位点沉积物的生物反应器中。使用被动采样器在 35 天内测量了顶部空间和水性生物反应器室中的 PCB 质量。对所有 209 种 PCB 同系物的时间序列测量显示，与非生物增强对照相比，生物增强处理的气相中积累的 PCB 总质量平均减少了 57%。同类物特异性比较分析显示 LB400 优先生物降解低氯 PCB (LC-PCB)。最丰富的同源物（PCB 4 [2,2'-二氯联苯]）的释放量减少了 90% 以上。 PCB 反应输运模型的模拟与实验观察结果密切相关。我们还评估了植物源生物表面活性剂皂苷对 LB400 的 PCB 生物利用度和生物降解的影响。联苯二加氧酶 ( bphA ) 基因的时间序列 qPCR 测量表明，与不含皂苷的处理相比，皂苷更好地维持了bphA丰度。这些发现表明，生物增强、好氧 PCB 降解微生物的活跃种群可以有效降低 PCB 排放，因此可能有助于最大限度地减少 PCB 污染地点周围社区的 PCB 吸入暴露。