Recent advances and optimization strategies for the microbial degradation of PCBs: From monocultures to microbial consortia

Polychlorinated biphenyls (PCBs) are a class of synthetic organic compounds that are widely distributed in the environment and have significant adverse effects on humans as well as the ecosystem. Many microorganisms that can degrade PCBs have been reported, including monocultures of bacteria and fungi, as well as natural and artificial microbial consortia. Generally, anaerobic dechlorination can degrade highly chlorinated PCBs to reduce their toxicity, while aerobic oxidation degrades lowly chlorinated PCBs (four or fewer chlorine atoms) and realizes their complete mineralization into CO2 by disrupting the benzene ring structure. Due to the need for the metabolism of a wide range of PCB congeners in the environment, microbial consortia have become a research hotspot, and their species diversity facilitates metabolic cooperation, enabling them to undertake more complex tasks. In this review, we will discuss the metabolic mechanisms of PCB degradation by monocultures as well as microbial consortia, and focus on the recent progress in the development and optimization of PCB-degrading microbial consortia, the community composition analysis methods, the prevailing optimization strategies such as biostimulation, bioaugmentation, metagenomics, and the combination of other methods for a better remediation effect, which will provide theoretical and practical bases for the rational design, construction and further optimization of efficient microbial consortia for the high-efficiency degradation of PCBs.