Coastal marine bacteria with hydrocarbon-degrading capacity: Isolation, screening, and genomic insights

Hydrocarbons, which are the primary constituents of crude petroleum and fuels such as diesel, are frequently introduced into the environment through oil spills, industrial discharges, and fuel leakages. Owing to their low solubility, chemical stability, and limited bioavailability, they impede natural attenuation processes, resulting in persistent contamination and the disruption of microbial ecosystems. In this study, 51 bacterial strains were isolated from the marine environment on a coastal island. These isolates were identified as species that have been previously reported to exhibit hydrocarbon-degrading abilities or other biotechnological attributes. A redox-based colorimetric assay was employed to preliminarily assess hydrocarbon and crude oil degradation. Six strains were identified that utilized hexadecane as a representative aliphatic hydrocarbon, while three strains demonstrated crude oil degradation. Among the tested strains, four isolates, specifically two Pseudomonas aeruginosa, one Acinetobacter oleivorans, and one Acinetobacter venetianus, exhibited outstanding degradation capabilities under challenging conditions, as confirmed by quantitative analysis. Additionally, strong emulsification activity and hexadecane-induced alkB1 expression further validated their functional roles in hydrocarbon degradation. Whole-genome sequencing further revealed the presence of key genes involved in alkane and aromatic compound catabolism as well as biosurfactant biosynthesis. This study highlights the significant potential of bacterial strains for applications in environmental bioremediation and industrial biotechnology.