Synergistic remediation of phenanthrene–cadmium co-contaminants by an immobilized acclimated bacterial–fungal consortium and its community response

Abstract

Bioremediation has tremendous potential to mitigate the serious threats posed by polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs). In the present study, nine bacterial-fungal consortia were progressively acclimated under different culture conditions. Among them, a microbial consortium 1, originating from activated sludge and copper mine sludge microorganisms, was developed through the acclimation of a multi-substrate intermediate (catechol)-target contaminant (Cd 2+ , phenanthrene (PHE)). Consortium 1 exhibited the best PHE degradation, with an efficiency of 95.6% after 7 d of inoculation, and its tolerance concentration for Cd 2+ was up to 1800 mg/L within 48 h. Bacteria Pandoraea and Burkholderia-Caballeronia-Paraburkholderia, as well as fungi Ascomycota and Basidiomycota predominated in the consortium 1. Furthermore, a biochar-loaded consortium was constructed to better cope with the co-contamination behavior, which exhibited excellent adaptation to Cd 2+ ranging of 50-200 mg/L. Immobilized consortium efficiently degraded 92.02-97.77% of 50 mg/L PHE within 7 d while removing 93.67-99.04% of Cd 2+ . In remediation of co-pollution, immobilization technology improved the bioavailability of PHE and dehydrogenase activity of the consortium to enhance PHE degradation, and the phthalic acid pathway was the main metabolic pathway. As for Cd 2+ removal, oxygen-containing functional groups (-OH, C=O, and C-O) of biochar or microbial cell walls and EPS components, fulvi…