Synergistic biochar-microbe interactions enhance petroleum contaminant removal and microbial community succession

Petroleum in soil poses a serious threat to the environment and human health. The remediation potential and mechanisms of oil sludge biochar (OBC) or rice husk biochar (RBC) combined with Pseudomonas putida (PS) remain unclear. A pot experiment was conducted with six treatments: control (CK), OBC alone, RBC alone, PS alone, OBC combined with PS (OBCPS), and RBC combined with PS (RBCPS). After 50 days, both OBCPS and RBCPS treatments demonstrated significantly higher degradation efficiencies for total petroleum hydrocarbon and polycyclic aromatic hydrocarbons compared to CK. Microbial analysis revealed that Proteobacteria and Firmicutes were the dominant phyla involved in petroleum degradation. Bacillus , Paenibacillus , Enterococcus , and C1-B045 were notably enriched in OBCPS and RBCPS, playing pivotal roles in soil remediation. Null-model analysis indicated that biochar-microbe synergy shifted the microbial community assembly from stochastic to deterministic processes. BugBase predicted enhanced recruitment of stress-tolerant microbes in combined treatments to improve remediation efficiency. This study confirms the strong synergistic potential of combining diverse biochars (OBC/RBC) with microorganisms (PS) for effective petroleum-contaminated soil remediation, offering a win-win strategy for solid waste recycling and ecological restoration. • Biochar combined with bacteria enhanced the degradation rate of TPH and PAHs. • Key hydrocarbon-degrading genera were enriched in biochar-microbe treatments. • Null-model analysis revealed biochar-microbe synergy shifted community assembly from stochastic to deterministic processes. • BugBase predicted biochar-microbe combinations recruited more stress-tolerant microbes.