Effects of electron donors on anaerobic microbial debromination of polybrominated diphenyl ethers (PBDEs)

Abstract

Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants that have been highly accumulated in sediments. It is reported that microorganisms play an important role in the reductive debromination of PBDEs in anaerobic sediments. However, little is known about the effects of electron donors on the microbial community structure and their debromination capacity in PBDE transformation. In this study, alternate carbon substrates were used as electron donors to enrich the PBDE-debrominating microbial consortia to evaluate the effects of electron donors on PBDE microbial debromination. Decabromodiphenyl ether (BDE-209) was found to be the dominant (more than 50%) PBDEs congener in all consortia, and the percentage of BDE-209 was deceased by 12% (methanol), 11% (ethanol), 8% (acetate), 9% (lactate), 5% (pyruvate), and 11% (no electron donors), while the relative abundances of most lesser-brominated PBDEs increased after 90-day incubation compared to the initial profile of PBDEs. Substantial shifts in the microbial community structure among different amendments were observed based on denaturing gradient gel electrophoresis results. Pseudomonas spp. were identified to be the predominant organisms and the abundances of Band R, which was associated with Pseudomonas sp. SCSWA09, was well correlated with the biodegradation rate of BDE-209. Finally, the microbial community structure was highly correlated with the concentration of deca-BDE, octa-BDE and total nitrogen. These results provide insights into in situ bioremediation of environments contaminated by PBDEs and our understanding of microbial ecology associated with PBDE-debromination.

Microbial communities associated with anaerobic degradation of polybrominated diphenyl ethers in river sediment

“…14 Here we found the classes Gammaproteobacteria, Clostridia, and Betaproteobacteria may be involved in anaerobic degradation of PBDEs. These results are similar to Qiu et al, 15 who reported the effects of electron donors on the anaerobic degradation of PBDEs. The genus Clostridium and Pseudomonas were present in anaerobic degradation of PBDEs.…”

Bar-Coded Pyrosequencing Reveals the Responses of PBDE-Degrading Microbial Communities to Electron Donor Amendments

“…The environmental data used in these analyses, such as the geochemical properties and the concentrations of PBDEs, were presented in our previous study [14]. At phylum level, the total organic carbon in sediment (S-TOC), chemical oxygen demand (COD) and the amount of deca-BDE (Deca-BDE) were detected as the top three highest loading environmental variables, which could significantly ( p  = 0.004) explain 92.0% of the total variance with 69.0% by the first axis and 28.3% by the second axis.…”

“…Lee and He [9] found that the amendment of trichloroethene (TCE) promoted the growth of Dehalococcoides species during the PBDEs debromination process. Our previous study also found that the amendment of electron donors (methanol, ethanol, acetate, lactate and pyruvate) substantially shifted the PBDE-degrading microbial community structure based on 16S rDNA DGGE analysis and the PBDE-degrading product profile [14]. However, due to the limited resolution of DGGE analysis, detailed information about the diversity, composition and structure of microbial communities from PBDE-degrading microcosms and their correlations with the environmental parameters remains elusive.…”

Dynamics of brominated flame retardants removal in contaminated wastewater sewage sludge under anaerobic conditions

“…It is known that higher brominated DEs are under anaerobic conditions debrominated to form lower brominated congeners. The transformation pathways and thus formation of debromination products is affected by the structure of the microbial community and/or the presence of an alternative carbon substrate used as electron donors (Lee and He, 2010;Qiu et al, 2012). Due to the mixture of PBDE congeners in sludge, it was difficult to express and compare the degradation rates for individual lower brominated congeners; however we can conclude that in both samples, the relative debromination removals of PBDEs were in the order hexa-and hepta-BDE, BDE 209, penta-BDE, and tetra-BDE (Table 1).…”

“…As majority of studies had focused on the debromination of individual BDE congeners (Gerecke et al, 2005;Nyholm et al, 2010;Qiu et al, 2012;Xu et al, 2012;Zhu et al, 2014) or the research was conducted using microbial enriched culture or pure strains Xu et al, 2014) we decided to study the removal of wide spectrum of PBDE congeners (PBDEs No. 28,47,49,66,85,99,100,153,154,183,209) and HBCD directly in industrially contaminated sewage sludge by autochthonous microflora.…”