Biodegradation of aryl-organophosphate flame retardants by Rhodococcus pyridinivorans YC-MTN: Performance, pathway and potential in environmental remediation

Abstract

A strain capable of efficiently degrading aryl-organophosphate flame retardants (aryl-OPFRs) was isolated and identified as Rhodococcus pyridinivorans YC-MTN. The strain demonstrated high degradation efficiency within a wide range of pH (7.0–10.0), temperature (25–45 °C), and salinity (0–2%). Strain YC-MTN effectively utilized aryl-OPFRs as the sole carbon source, facilitating their rapid degradation. The estimated half-lives for four aryl-OPFRs, namely triphenyl phosphate (TPhP), tricresyl phosphate (TCrP), 2-ethylhexyl diphenyl phosphate (EHDPP), and resorcinol bis (diphenyl phosphate) (RBDPP), were found to be 8.73, 10.82, 30.28, and 16.14 h, respectively. Additionally, half of the aryl-OPFRs underwent mineralization after 7 d of incubation. In particular, hydrolysis played a dominant role in the metabolism of TPhP, EHDPP, and RBDPP by strain YC-MTN, while P–O bond cleavage generally occurred in the presence of phenol as the leaving group. In addition to hydrolysis, methylation participated in the biotransformation of TCrP. Strain YC-MTN exhibited significant degradability towards TPhP at various concentrations ranging from 1 to 1000 mg L−1. The remediation of TPhP was simulated in both freshwater and seawater, and within a span of 5 d, strain YC-MTN completely degraded the exogenous TPhP. Strain YC-MTN holds potential as a viable microbial agent in the bioremediation of aryl-OPFRs contamination.