Characterization of C16–C36 alkane degradation and oily sludge bioremediation by Rhodococcus erythropolis XP

ABSTRACT Oil contamination poses significant risks to human health and ecosystems, emphasizing the importance of studying alkane biodegradation. In this study, we found that Rhodococcus erythropolis XP can utilize various alkanes, including C16–C36 n- 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 n- alkanes. Notable biodegradation of C14–C30 alkanes was observed in sludge treated with Rhodococcus erythropolis XP. In addition, metabolic intermediates of C16 and C20 were identified, indicating the presence of both terminal and subterminal pathways in Rhodococcus erythropolis XP. A new Baeyer-Villiger monooxygenase (BVMO₄041) was characterized, which catalyzes a key step in the subterminal pathway of alkane degradation. These results reflect the promise of Rhodococcus erythropolis XP in addressing the pressing need for efficient alkane degradation in contaminated environments. IMPORTANCE Oil 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, Rhodococcus erythropolis XP has been proved to obtain the almost strongest ability to degrade C16–C36 n -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 BVMO₄041 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.