Microbial Community Dynamics in Marine Water: Influence of Hydrocarbon Type and Exposure Time

Marine environments are frequently impacted by petroleum-derived hydrocarbons, which pose ecological risks because of their toxic, mutagenic, and carcinogenic potential. Microorganisms play a crucial role in hydrocarbon degradation, and understanding the influence of time and hydrocarbon type on microbial dynamics helps improve bioremediation strategies. In this study, marine water samples were used to assemble microcosms containing different hydrocarbon contaminants (naphthalene-NAF, crude oil-OL, and a synthetic mixture-MIX) and were incubated for 7, 15, 30, 45, and 60 days under controlled conditions. The bacterial community structure and composition were analyzed via 16S rRNA gene sequencing combined with functional prediction via PICRUSt2. Alpha diversity differed significantly among contaminants, with OL and MIX supporting more diverse communities. Beta diversity was shaped by both contaminant type and incubation time. Hydrocarbon-degrading taxa such as Marinobacter, Alteromonas, Pseudomonas, and Thalassospira dominated at different stages, which was consistent with a functional progression from aliphatic oxidation (K00496) to successive steps of aromatic ring degradation (K00529, K00448, K07104). Together, these results demonstrate that hydrocarbon type and exposure time shape microbial succession, driving taxonomic differentiation and metabolic specialization, and providing insights for improving bioremediation strategies in marine environments.