Bioremediation of Oil Shale Residue Using a Novel N-Hexadecane-degrading Consortium: Degradation Performance and Underlying Mechanisms

Long-chain alkanes in oil shale residue are persistent pollutants that threaten environmental safety. Using n-hexadecane (n-C16) as a model compound, we isolated a hydrocarbon-degrading microbial consortium from the residue and elucidated its metabolic mechanism. Three dominant strains—Pseudomonas stutzeri, Achromobacter xylosoxidans, and Aspergillus ochraceus —were identified and formulated into a composite consortium at an optimized cell abundance ratio of 2.0:3.0:1.0 (CFU basis, P. stutzeri: A. xylosoxidans: A. ochraceus), with a total viable count of~1.0×109 CFU·mL-1. Under conditions determined by response surface methodology, the consortium achieved 98.6% n-C16 degradation within 7 days. GC-MS analysis revealed a complete four-stage pathway: substrate uptake and emulsification, terminal oxidation (n-C16 → hexadecanol → hexadecanal → hexadecanoic acid), β-oxidation, and downstream mineralization. The functional complementarity among consortium members effectively eliminated metabolic bottlenecks, ensuring complete degradation. This work establishes a practical bioremediation framework for oil shale residue, converting it into a detoxified product suitable for safe land application, and offers a sustainable waste management solution for the unconventional energy sector.