Functional characterization of an efficient chloroxylenol-degrading bacterial consortium

Chloroxylenol (synonym, para-chloro-meta-xylenol [PCMX]), a halogenated phenolic disinfectant, is widely used for disinfection or in personal care products. Due to the global COVID-19 pandemic, the widespread use of PCMX has undoubtedly led to its prevalence in various environments, resulting in a high detection frequency. However, there have been few reports on the aerobic microbial community and pure culture degradation of PCMX. In this study, a PC2 consortium with an efficient PCMX decomposition was successfully obtained. Rhodococcus was significantly enriched in consortium PC2 after the acclimation. Subsequently, a PCMX-degrading pure culture strain, Rhodococcus sp. JH-7, was isolated, and the degradation characteristics were investigated. Meanwhile, a key metabolic intermediate (4-chloro-3,5-dimethylcatechol) was identified by LC-TOF-MS and a new biodegradation pathway of PCMX was proposed. Additionally, Rhodococcus sp. JH-7 could protect Escherichia coli, Pichia pastoris, Chlorella ellipsoidea and Chlamydomonas reinhardtii from the toxicity of PCMX, indicating that the biodegradation of PCMX was a detoxification process. This study reveals a catabolic pathway of PCMX and provides new insights for the bioremediation of PCMX-contaminated environments.