Phenanthrene Degradation by Multi-Site-Derived Mixed Bacterial Consortia in Contaminated Wastewater Under Specific Environmental Conditions: Responses of Community Characteristics

Microbial remediation technologies have emerged as a promising strategy for polycyclic aromatic hydrocarbon (PAH) removal; however, single strains are often constrained by limited metabolic pathways and PAH toxicity, and the response patterns of bacterial consortia to interacting environmental drivers remain poorly elucidated. Herein, culturable individual bacterial consortia were enriched from soils of three typical contaminated sites, and culturable mixed bacterial consortia were constructed via binary and ternary combinations. The phenanthrene (a representative PAH) degradation performance and community characteristics of these consortia under specific environmental conditions were systematically evaluated by orthogonal experimental design; range and variance analyses were employed to identify the primary influencing factors. Results revealed that mixed consortia (83.69%) exhibited stronger phenanthrene degradation efficiency compared to individual consortia (50.55%). Statistical analysis further identified phenanthrene concentration and temperature as primary factors influencing phenanthrene degradation efficiency and bacterial diversity. Meanwhile, elevated phenanthrene concentration increased OTU counts, while phylum-level and genus-level compositions exhibited greater sensitivity to temperature. Functionally, metabolic dominated KEGG pathways of Level 1, with higher temperature inhibiting the abundance of functional genes by phenanthrene degradation. Overall, the culturable mixed bacterial consortia constructed in this study are capable of effectively removing phenanthrene from wastewater under specific environmental conditions, laying a solid theoretical and practical foundation for PAH remediation.