Microbial consortium degrading of organic pollutants: Source, degradation efficiency, pathway, mechanism and application

Toxic organic pollutants in the environment cause potential threats to ecosystem and human health. Microbial consortia demonstrate efficient degradation of organic pollutants and bioremediation. Here, we summarized the main sources of microbial consortia, and discuss the degradation efficiencies, pathways and mechanism of different organic pollutants. Current enriched microbial consortia including bacteria and fungi are derived mainly from sediment, contaminated soil, and sewage sludge. The enriched or synthetic microbial consortia generally exhibit high degradation efficiencies (∼100%) for polycyclic aromatic hydrocarbons, total petroleum hydrocarbons and phthalates, while relatively low degradation efficiencies (∼85%) for polychlorinated biphenyls. Microbial consortia display more proficient degradation of organic pollutants than the individual strains (or co-culture than monoculture). These organic pollutants can be degraded by microbial consortia through different pathways as confirmed by the identified intermediates. Interestingly, these pollutants share the similar downstream degradation pathways via phthalic acid, benzoic acid (or benzoate), catechol, and ring-cleavage pathways in spite of their differentiation in upper degradation pathways. The degradation mechanisms of organic pollutants by consortia are reviewed and their biochemical pathways are reconstructed based on crucial pollutant-degraders and functional genes annotated by high-throughput sequencing and/or metagenomics. Here, it is the first time to summarize the common biodegradation pathways for multiple classes of organic pollutants by microbial consortia. Notably, some key species of microbial consortia play important roles in biodegradation and transformation of organic pollutants, and can remove pollutants via co-metabolism and bacterial-fungal interaction. Furthermore, microbial consortia significantly promote pollutant removals from wastewater, the contaminated sediment and soil, suggesting their potential boarder applications. Finally, we highlighted knowledge gaps and prospects for researches, such as achieving more versatile microbial consortia, exploring biodegradation efficiencies and mechanism for recalcitrant persistent/emerging organic pollutants and the interaction of bacterial-fungal consortia.