posted on 2023-12-19, 22:29authored byGuiping Liu, Kai Chen, Zhiming Wu, Yanhan Ji, Lianghua Lu, Songmeng Liu, Zhi-Ling Li, Rong Ji, Shuang-Jiang Liu, Jiandong Jiang, Wenjing Qiao
Tetrabromobisphenol
A (TBBPA), a widely used brominated flame retardant
in electronics manufacturing, has caused global contamination due
to improper e-waste disposal. Its persistence, bioaccumulation, and
potential carcinogenicity drive studies of its transformation and
underlying (a)biotic interactions. This study achieved an anaerobic
enrichment culture capable of reductively dehalogenating TBBPA to
the more bioavailable bisphenol A. 16S rRNA gene amplicon sequencing
and quantitative PCR confirmed that successive dehalogenation of four
bromide ions from TBBPA was coupled with the growth of both Dehalobacter sp. and Dehalococcoides sp.
with growth yields of 5.0 ± 0.4 × 108 and 8.6
± 4.6 × 108 cells per μmol Br– released (N = 3), respectively. TBBPA dehalogenation
was facilitated by solid humin and reduced humin, which possessed
the highest organic radical signal intensity and reducing groups −NH2, and maintained the highest dehalogenation rate and dehalogenator
copies. Genome-centric metatranscriptomic analyses revealed upregulated
putative TBBPA-dehalogenating rdhA (reductive dehalogenase)
genes with humin amendment, cprA-like Dhb_rdhA1 gene in Dehalobacter species, and Dhc_rdhA1/Dhc_rdhA2 genes in Dehalococcoides species. The upregulated
genes of lactate fermentation, de novo corrinoid
biosynthesis, and extracellular electron transport in the humin amended
treatment also stimulated TBBPA dehalogenation. This study provided
a comprehensive understanding of humin-facilitated organohalide respiration.