High hydrostatic pressure stimulates n-C₁₆ mineralization to CO₂ by deep-ocean bacterium Alcanivorax xenomutans A28

Medium-chain alkanes have strong ecological impacts on marine ecosystems due to their persistence, toxicity, and ability to travel long distances. Microbial degradation is the dominant and ultimate removal process for n-alkanes in the deep ocean, where high hydrostatic pressure (HHP) regulates microbial activity. To gain insight into the impact of hydrostatic pressure (HP) on n-alkane degradation, we applied the deep-ocean experimental simulation to culture Alcanivorax xenomutans A28, a novel piezotolerant bacterium strain from trench sediment, with n-C₁₆ as the sole carbon source under different HPs (0.1, 40, and 80 MPa). Activity analysis demonstrated that HHP stimulated the n-C₁₆ complete mineralization ratio. Transcriptomic and metabolomic analyses showed that HHP induced the intracellular oxidative stress and accelerated the tricarboxylic acid (TCA) cycle. These results indicate a shift of n-alkanes biodegradation pattern regulated by HP, elucidating the fate and ecological risk of n-alkanes in the deep ocean.