Integrated toxicology, metabolomics, and transcriptomics analyses reveal the biodegradation and adaptation mechanisms to BDE-47 in Pseudomonas plecoglossicida

Abstract

Microbial degradation technology is often considered as an eco-friendly and cost-effective strategy to reduce the risks of 2,2′,4,4′-tetrabrominated diphenyl ether (BDE-47). However, the number of available BDE-47-degradating bacteria is insufficient, and there has yet to fully understand the biotransformation mechanisms of BDE-47. Here, a new strain, P. plecoglossicida, was isolated for the BDE-47 degradation. The biodegradation and adaption mechanisms of P. plecoglossicida to BDE-47 were systematically examined through an integrative approach combining toxicological assessment, degradation product analysis, metabolomic analysis, and transcriptomic analysis. Toxicological assessment and metabolomic analysis indicated that the adaptation mechanism of P. plecoglossicida to BDE-47 was mainly activating the antioxidant defense system to relieve the oxidative stress induced by BDE-47. However, the defense ability of P. plecoglossicida against BDE-47 was limited, and the high concentration of BDE-47 would result in the disturbance of amino acid and purine metabolism, and ultimately apoptosis. The analysis of degradation products and transcriptomics revealed that BDE-47 underwent debromination, hydroxylation, ether bond breaking, and ring-opening cleavage with the participation of multiple intracellular oxidoreductases. Besides, active efflux of BDE-47 and its degradation products mediated by efflux pump and multiple transporters might contribute to the bacterial tolerance against them. These results provided greater insights into the mechanisms of BDE-47 biodegradation.