Artificially synthesized bacterial consortia improve remediation of As-PAHs co-contaminated soil: rational design, efficiency improvement, and environmental parameter regulation

Artificially constructed microbial consortia offer a promising strategy for remediating soils co-contaminated with heavy metals and organic pollutants. However, the functional roles of individual members and the environmental responses of such consortia remain insufficiently understood. In this study, a synthetic bacterial consortium composed of Rhodococcus qingshengii , Sphingomonas paucimobilis , and Xanthobacter agilis was assembled for the remediation of As-PAHs co-contaminated soil. After 7 days of incubation, the consortium achieved 65.6% PAHs degradation, representing a 16.6% increase relative to the control, whereas the increase in arsenic oxidation was limited (26.9% vs. 25.8% in the control). Comparative experiments showed that the three-strain consortium outperformed individual strains and binary combinations, with residual PAHs decreasing to 0.246 mg/kg and the proportion of As(V) increasing to 72.4% after 14 days. These results support the use of the consortium over simpler strain combinations and suggest non-additive functional interactions among the selected strains. Supplementation with vitamin B 2 , vitamin B 12 , and siderophore further improved PAHs degradation, with siderophore showing the strongest enhancement of PAHs removal. Moisture-controlled experiments suggested that the enhanced remediation performance was mainly associated with biological activity rather than moisture input alone. Environmental parameter analysis showed that the consortium remained active across pH 5.0–9.0 and 15–30 °C, with stronger PAHs removal under neutral to mildly alkaline conditions and at higher temperatures. Overall, this study demonstrates that rational consortium design can enhance PAHs removal in As-PAHs co-contaminated soil and provides a preliminary basis for understanding strain complementarity and environment-dependent remediation responses in synthetic microbial systems.