title: Isolation of Acetobacterium sp. strain AG, which reductively debrominates octa- and pentabrominated diphenyl ether technical mixtures.
abstract: Polybrominated diphenyl ethers (PBDEs) are a class of environmental pollutants that have been classified as persistent organic pollutants since 2009. In this study, a sediment-free enrichment culture (culture G) was found to reductively debrominate octa- and penta-BDE technical mixtures to less-brominated congeners (tetra-, tri-, and di-BDEs) via a para-dominant debromination pattern for the former and a strict para debromination pattern for the latter. Culture G could debrominate 96% of 280 nM PBDEs in an octa-BDE mixture to primarily tetra-BDEs in 21 weeks. Continuous transferring of culture G with octa-/penta-BDEs dissolved in n-nonane or trichloroethene (TCE) yielded two strains (Acetobacterium sp. strain AG and Dehalococcoides sp. strain DG) that retained debromination capabilities. In the presence of lactate but without TCE, strain AG could cometabolically debrominate 75% of 275 nM PBDEs in a penta-BDE mixture in 33 days. Strain AG shows 99% identity to its closest relative, Acetobacterium malicum. In contrast to strain AG, strain DG debrominated PBDEs only in the presence of TCE. In addition, 18 out of 19 unknown PBDE debromination products were successfully identified from octa- and penta-BDE mixtures and revealed, for the first time, a comprehensive microbial PBDE debromination pathway. As an acetogenic autotroph that rapidly debrominates octa- and penta-BDE technical mixtures, Acetobacterium sp. strain AG adds to the still-limited understanding of PBDE debromination by microorganisms.
authors.affiliation: Department of Civil and Environmental Engineering, National University of Singapore, Singapore.
authors.forename: Chang
authors.initials: C
authors.lastname: Ding
authors.forename: Wai Ling
authors.initials: WL
authors.lastname: Chow
authors.forename: Jianzhong
authors.initials: J
authors.lastname: He
mesh_terms: D045855:Acetobacterium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D001711:Biotransformation; D041862:Chloroflexi / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D004785:Environmental Pollutants / Q000378:metabolism*; D055768:Halogenated Diphenyl Ethers / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004785:Environmental Pollutants; D055768:Halogenated Diphenyl Ethers; D012336:RNA, Ribosomal, 16S