Continuous exogenous bioaugmented remediation of petroleum-contaminated soil: Ecological effects, microbial...

The exogenous bioaugmentation technique is a widely employed strategy for remediating petroleum-contaminated soil. However, sustaining exogenous functional bacteria over extended periods in complex petroleum-contaminated environments is challenging, leading to reduced efficacy, and the interaction mechanisms with indigenous microorganisms remain poorly understood. This study utilized the previously developed petroleum-degrading bacterial agent ECT in a continuous bioaugmentation (C-Bio) approach for soil remediation. The outcomes were compared with those from a disposable bioaugmentation (D-Bio) and a control group (CG). After a 200-day remediation period, the C-Bio approach achieved a simulated petroleum degradation rate of 99.42 %. Concurrently, assessments of soil physicochemical properties, enzyme activities, and plant growth demonstrated that C-Bio resulted in favorable ecological restoration. Metagenomic analysis confirmed the successful colonization of the three exogenous bacteria in the C-Bio system. Network analysis revealed that this approach facilitated the directional succession of soil microbial communities, with the newly dominant indigenous bacteria forming cooperative or symbiotic relationships with the exogenous strains. Together, they synergistically degrade alkanes via terminal oxidation pathways and aromatic hydrocarbons through salicylic acid and phthalic acid pathways, leading to effective remediation of petroleum-contaminated soil. This study offers theoretical insights and empirical evidence supporting the development of continuous bioaugmentation processes for the remediation of petroleum-contaminated soils.