Enhanced degradation of phenanthrene in microalgae-bacteria synergistic system: Comparison of the synergistic mode and regulation mechanism between exogenous and indigenous degrading bacteria_16s-seq
This study investigates the distinct cooperative modes of two microalgal-bacterial consortia-endogenous (C.v-EB) and exogenous (C.v-IB)-in enhancing the growth of Chlorella vulgaris and the biodegradation of PHE. Compared to monocultures, the cooperative systems demonstrated superior performance, with C.v-IB and C.v-EB increasing biomass by 75% and 17.2%, respectively, and significantly higher PHE removal rates. Mechanistically, C.v-EB relied primarily on enzymatic antioxidant defenses and a convergent degradation pathway centered on catechol ring cleavage. In contrast, C.v-IB utilized non-enzymatic redox regulation, a robust photoprotective response, and a denser, biofilm-like EPS matrix to enhance metabolic signaling and interfacial transport. Metagenomic analysis further revealed that C.v-EB was driven by deterministic assembly, enriching genes for cell wall biogenesis, whereas C.v-IB maintained a neutral community assembly with higher metabolic redundancy. Integrated LC-MS and toxicological analysis confirmed that C.v-IB's parallel multi-pathway degradation effectively prevented the accumulation of toxic intermediates, thereby mitigating environmental risks. These findings provide a comprehensive theoretical framework for engineered bioremediation and offer a scientific basis for the strategic selection of tailored microalgal-bacterial consortia to optimize the treatment of specific polycyclic aromatic hydrocarbon pollutants.