Characterization of hydrocarbons and associated bacterial communities in the Pacific WWII shipwreck oil.

This study investigates the hydrocarbon composition and bacterial communities present in fuel oil retrieved from World War II shipwrecks in the Pacific. We quantified Total Petroleum Hydrocarbons (TPH), Benzene, Toluene, Ethylbenzene, and Xylene (BTEX), as well as Polyaromatic Hydrocarbons (PAHs) using Gas Chromatography - Flame Ionization Detection and Mass Spectrometry (GC-FID/GC-MS). Additionally, we profiled the bacterial community using the V3/V4 regions of the 16S rRNA gene, identifying a diverse microbial assemblage comprising 42 phyla, 107 classes, 249 orders, 432 families, 1047 genera, and 1505 species. Dominant phyla included Proteobacteria (77.9%), Actinobacteriota (35.7%), Firmicutes (19%), and Bacteroidota (6.1%). While active hydrocarbon degradation was not directly assessed, the presence of known hydrocarbon-associated taxa highlights a community structured around long-term hydrocarbon exposure. The distribution of microbial communities appeared to be influenced by both hydrocarbon composition and sampling location. Fuel oil from one site was a blend of distillate and residual oils with higher concentrations of BTEX and PAHs, while the other was only, with higher overall PAH and TPH levels. These findings offer valuable insights into the microbial community structure in historically contaminated marine environments and establish a baseline for future research. This study contributes to broader efforts in pollution monitoring, ecosystem conservation, and establishes a taxonomic baseline to inform future functional bioremediation research.