• • Consortium MC-5 (SDB1:SDB2:SDB3:SDB4 = 1:1:0:3) achieved 83.46% TPH degradation in liquid culture, outperforming all single strains and other consortia, demonstrating the critical role of optimized microbial community composition in maximizing hydrocarbon mineralization.
• • Combined ryegrass and MC-5 remediation yielded 60.93% soil TPH degradation, a 54.26 percentage point increase over the control, and degraded recalcitrant resins/asphaltenes by 49.44%, proving that synergistic plant-microbe systems can tackle both labile and recalcitrant petroleum fractions.
• • Microbial consortium contributed 63%–69% to TPH removal, while plant contribution was only 2%–12% and confined to the later remediation phase, indicating that microbial activity is the primary driver and plant effects are auxiliary, which informs resource allocation in field-scale bioremediation.
• • Rhamnolipid amendment further increased TPH degradation by 7.05 percentage points in the combined system, highlighting the potential of biosurfactants to enhance bioavailability and microbial activity, thereby improving overall remediation efficiency.