Microbial degradation of 1,2-bis(2,4,6-tribromophenoxy)ethane by a novel bacterial isolate: transformation mechanism and bioaugmentation.

To date, reports on the microbial degradation of 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE) by pure strains remain limited. Herein, a BTBPE-degrading strain--FX-1--affiliated with Bacillus velezensis was isolated for the first time. After 5 days of reaction, a maximum biodegradation efficiency of 72.6% was achieved for 1.0 mg/L BTBPE in the presence of 1.0 g/L glucose as a co-substrate at an initial pH of 7.2 and a temperature of 30°C. Eight identified biodegradation products indicated that debromination, ether bond cleavage and aromatic ring cleavage were the primary biotransformation pathways for BTBPE. Biodegradation by strain FX-1 was shown to reduce the biotoxicity of BTBPE. Integrated analysis of proteomics and RT-qPCR suggested that chemotaxis proteins, ABC transporters, and lipoproteins might facilitate the transmembrane transport of BTBPE. Haloacid dehalogenase, nitrate reductase, and cytochrome P450 enzymes were potentially involved in the biotransformation of BTBPE. Histidine kinase, response regulator, general stress proteins, antioxidant proteins, and chaperone proteins might support the survival of strain FX-1 under BTBPE stress. The addition of 1.0-g/L glucose enhanced the expression of BTBPE-degrading enzymes and stress-responsive proteins. Microcosm experiments suggested that strain FX-1 was a promising candidate for the bioaugmentation of BTBPE-contaminated water, sediment, and soil. To the best of our knowledge, this is the first study to illuminate the mechanisms of BTBPE transformation by a bacterial strain and propose its potential use in bioremediation.