Characterization of C16–C36 alkane degradation and oily sludge bioremediation by <i>Rhodococcus erythropolis</i> XP

Oil contamination poses significant risks to human health and ecosystems, emphasizing the importance of studying alkane biodegradation. In this study, we found that <i>Rhodococcus erythropolis</i> XP can utilize various alkanes, including C16-C36 <i>n-</i>alkanes and iso-alkane (pristane). The degradation capacity was significant, with over 95% of C20 degraded (500-2,500 mg/L) within 72 h. The bioremediation capacity in oily sludge was determined by a novel Low Pressure Gas Chromatography-Mass Spectrometry methodology especially for rapid analysis (within 12 min) of <i>n-</i>alkanes. Notable biodegradation of C14-C30 alkanes was observed in sludge treated with <i>Rhodococcus erythropolis</i> XP. In addition, metabolic intermediates of C16 and C20 were identified, indicating the presence of both terminal and subterminal pathways in <i>Rhodococcus erythropolis</i> XP. A new Baeyer-Villiger monooxygenase (BVMO_4041) was characterized, which catalyzes a key step in the subterminal pathway of alkane degradation. These results reflect the promise of <i>Rhodococcus erythropolis</i> XP in addressing the pressing need for efficient alkane degradation in contaminated environments.IMPORTANCEOil pollution posed a severe threat to human health and environmental safety due to its chemical stability and prolonged persistence. Although a lot of bacteria have been reported to degrade alkanes, the main components in oil pollution, it is urgent to identify strains that can degrade medium- and long-chain alkanes and to evaluate their performances during bioremediation. In this study, <i>Rhodococcus erythropolis</i> XP has been proved to obtain the almost strongest ability to degrade C16-C36 <i>n</i>-alkanes and branched alkanes (pristane), and to be a promising option for oily sludge bioremediation with newly developed rapid detection technology based on low pressure gas chromatography-mass spectrometry. Meanwhile, the metabolic pathways and a new <i>BVMO_4041</i> gene encoding Baeyer-Villiger monooxygenase were revealed. Our research provides a promising candidate for both practical bioremediation efforts and microbial research, and enriches the strain and gene resources for oil degradation.