Microbial community analysis of switchgrass planted and unplanted soil microcosms displaying PCB dechlorination

Abstract

Polychlorinated biphenyls (PCBs) pose potential risks to human and environmental health because they are carcinogenic, persistent and bioaccumulative. In this study we investigated bacterial communities in soil microcosms spiked with PCB 52, 77 and 153. Switchgrass (Panicum virgatum) was employed to improve overall PCB removal and redox cycling (i.e. sequential periods of flooding followed by periods of no flooding) was performed in an effort to promote PCB dechlorination. Lesser chlorinated PCB transformation products were detected in all microcosms, indicating the occurrence of PCB dechlorination. Terminal restriction fragment length polymorphism (T-RFLP) and clone library analysis showed that PCB spiking, switchgrass planting and redox cycling affected the microbial community structure. Putative organohalide-respiring Chloroflexi populations, which were not found in unflooded microcosms, were enriched after two weeks of flooding in the redox-cycled microcosms. Sequences classified as Geobacter sp. were detected in all microcosms, and were most abundant in the switchgrass-planted microcosm spiked with PCB congeners. The presence of possible organohalide-respiring bacteria in these soil microcosms suggests they play a role in PCB dechlorination therein.

Phytoremediation, Bioaugmentation, and the Plant Microbiome

“…Microzones and variable redox conditions allowed both aerobic and anoxic degradation pathways to exist in the same contaminated plant/soil systems for polychlorinated biphenyls (PCBs) phytoremediation. − However, oxygen is critical for the aerobic degradation of total petroleum hydrocarbons (TPH) in the subsurface by phytoremediation . Often, a “smear zone” exists at former refineries and tank farm sitesan oily phase at a depth under low oxygen conditions through which roots cannot penetrate .…”

Análise dos parâmetros que interferem no metabolismo da microbiota anaeróbia e anóxica na remoção de bifenilas policloradas

“…Assim, a identificação destes microrganismos no inóculo pode ser explicada pela sua importância ecológica em reatores metanogênicos. A ausência de identificação desses representantes nas amostras do final da operação, provavelmente, pode estar relacionada com a presença do PCB, que afetou a estrutura microbiana (LIANG et al, 2015) e ocasionou a seleção de microrganismos resistentes.…”