Modulation of Marine Bacterial Communities Exposed to Different Petroleum Hydrocarbons

Accidental petroleum spills in marine waters impact biodiversity and human health due to the toxicity and mutagenicity of hydrocarbons. Hydrocarbon-degrading bacteria are involved in decontamination processes, and understanding their dynamics in a contamination scenario can be helpful for the development of bioremediation strategies. This study investigated the modulation of bacterial communities in the presence of various petroleum hydrocarbons. Marine water samples were used to establish microcosms with different types of aliphatic (AL), monocyclic aromatic (MAH), polycyclic aromatic (PAH) hydrocarbons and a mixture of all contaminants (MIX) and crude oil (OL). Alpha and beta diversity, as well as bacterial group interactions, were analyzed based on valid 16S rRNA sequences obtained after quality filtering and processing. Proteobacteria was the most abundant phylum (42–73%) among the different contaminants. Different bacterial groups were enriched or depleted depending on the contaminant, and phenanthrene induced the greatest shifts on bacterial abundance, leading to an increase of Pseudomonas abundance (t test, P = 0.02), for example. Most of the dominant genera (e.g.: Pseudomonas, Thalassospira, Alteromonas and Marinobacter) were previously associated with hydrocarbon degradation. The AMP group (MIX and OL) exhibited distinct taxonomic distribution (PERMANOVA, P < 0.001) and interactions, reinforcing the impact of multiple hydrocarbons on microbial succession. Functional predictions revealed enrichment of hydrocarbon degradation genes, particularly those involved in hexane, benzene, and toluene breakdown. These findings improve understanding of microbial responses to hydrocarbon contamination, which is valuable for establishing effective bioremediation strategies, optimizing pollutant degradation and enhancing environmental sustainability.