Metagenomic Studies on Microbiomes Capable of Degrading the Decabromodiphenyl Ether in River Sediments

Abstract

Sediment contamination is a prevailing global environmental problem. Sediments in the lower sections of rivers are often contaminated by persistent organic pollutants (POPs). Among the POPs, polybrominated diphenyl ethers (PBDEs) raised deep concerns because of their multiple toxicities and endocrine-disrupting effects. Decabromodiphenyl ether (BDE-209) usually occupies more than 90% of the total PBDE concentration in sediments and is not easy to clean up. We have successfully developed the in situ phase inversion emulsification and biological reductive dehalogenation (ISPIE/BiRD) to remediate weathered polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) in river sediments. Still, it has yet to be applied to BDE-209-contaminated sediments. Thus, in this study, we tested ISPIE/BiRD’s applicability on the sediments contaminated by BDE-209 in batch and column experiments and analyzed their metagenomic profiles. In the batch experiment, the best-performing group, Group 3, removed 56.5% of BDE-209 in 70 days. In the column study, ISPIE removed 22% and 15% of BDE-209 in the weathered and fresh groups, respectively. In addition, the best performance group for subsequent BiRD removal is the natural recovery group of weathered BDE-209 (WNR), with a total removal of 56.0%. According to the DNA sequencing data, more species and higher diversity in the batch experiment tend to perform better. The predominant bacteria in the column experiment differed from those in the batch experiment but showed similar removal functions. Rectinema cohabitans is the only species positively correlated with the removals in batch and column studies. The results suggested that ISPIE/BiRD is feasible for the remediation of BDE-209-contaminated sediment.