Microbial ecology and genetics of benzalkonium chloride biotransformation in the environment
2017
Ertekin, E.
Contamination of the environment with biocides such as quaternary ammonium compounds (QACs) has been associated with public health and environmental hazards such as proliferation of antimicrobial resistance and ecotoxicity. Biodegradation of benzalkonium chloride (BAC), the most commonly used type of QAC biocides, is initiated with the conversion of BAC to benzyldimethyl amine (BDMA) via an N-dealkylation reaction. This reaction removes the biocidal activity of the BAC thus eliminates its impact in the environment. However, the structure of BAC degrading microbial communities is not fully understood as well as the genes involved in the BAC biodegradation pathway. In this study, it was demonstrated that a novel BAC degrader Pseudomonas sp. BIOMIG1 played a key role for BAC degradation in the environment. Whole genomes of four BIOMIG1 phenotypes revealed that a gene cluster specific to the former two strains was likely involved in converting BAC to BDMA, which is the key step in the pathway. This gene cluster consisted a Rieske oxygenase (oxyBAC), which was the only catabolic gene that was homologous to those transforming QAC-like compounds. E. coli transformed with oxyBAC could transform BAC into equimolar amounts of BDMA, confirming its function as a novel enzyme catalyzing an unusual dealkylation reaction.
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