Design and verification of a microbial consortium with an anchoring-interface enhancement strategy for efficient PAHs degradation in groundwater

Polycyclic aromatic hydrocarbons (PAHs) threaten 30% of drinking water sources worldwide. Compared to single strains or physicochemical approaches, microbial consortium provides a more stable and adaptive solution for complex groundwater remediation. Existing construction strategies focus too much on static degradation rates but overlook microbial migration under hydrodynamic disturbances. This leads to overestimations of dynamic remediation performance. Informed by the unique structural and functional traits of microorganisms, this study developed a microbial consortium capable of anchoring in groundwater porous media and enhancing interfacial bioavailability. Three strains were selected from 100 candidates to form the consortium: Agrobacterium pusense BN2 (anchoring via slime layer), Pseudoxanthomonas beigongshangi FL2 (bioavailability enhancement), and Pseudoxanthomonas beigongshangi BN8 (high degradation). This consortium degraded 16.02 mg/L of phenanthrene. It was found that Agrobacterium pusense BN2′s slime layers exhibit a dual regulatory mechanism: β-Sheet/α-Helix proteins form a highly stable corona that drives microbial consortium transport toward the pollutant source; the polysaccharide matrix anchors the microbial consortium to the pollutant source and resists water flow impact to regulate transport and anchoring. In a saturated soil microcosm, the microbial consortium increased the bioavailability of difficult to degrade bulk crystalline PAHs to 39.1 mg/kg. Ecological acute toxicity decreased by 88.3% compared to the phenanthrene contaminated control group. This mechanism results from the cooperative effects within the microbial consortium. It is also linked to the increased abundance of key genes in the degradation pathway. This study provided a new design perspective and paradigm for the design of application oriented microbial consortium, and offered a framework to construct remediation strategies based on bacterial functional structures for PAHs removal in groundwater dynamic environments.