Naphthalene-Degrading Bacteria with Potential for Remediating Marine Environments

Brazil is one of the largest oil producers in the world, and petroleum exploration is predominant in marine environments, mainly in the city of Rio de Janeiro. These environments become vulnerable to oil spills, which can be remedied by petroleum hydrocarbon-degrading bacteria. To better understand the distribution of polycyclic aromatic hydrocarbon (PAH)-degrading bacteria in these marine environments, water samples were collected from eight beaches (Arpoador, Grumari, Vermelha, Sahy, Itacuruçá, Itaipuaçu, Ferradura, and Itaipu) along the Rio de Janeiro coastline and further contaminated with 0.1% naphthalene, used as a PAH model. Naphthalene-enriched bacteria were isolated in marine agar, identified using 16S rRNA sequencing, and tested for emulsification and naphthalene degradation. Thirty-five different genera were observed among the 231 isolates, most belonging to Proteobacteria. Some genera were found in at least half of the studied beaches, such as Mesoflavibacter, Muricauda, Alteromonas, Salipiger, Pseudooceanicola, and Celeribacter, while others were found in only a few water samples. Seventeen and 18 strains were considered to be positive for naphthalene degradation and emulsification, respectively, making them the most promising strains for naphthalene bioremediation. Five of these strains were positive for both degradation and emulsification. This study contributes to the selection of potential candidates for further studies on the remediation of PAHs in tropical marine environments worldwide.