| Congresso Brasileiro de Microbiologia 2023 | Resumo: 221-1 | ||||
Resumo:Brazil is among the ten largest oil producers in the world, and its exploration is predominant in marine environments. Thus, these environments become vulnerable to possible oil spills, which can cause damage to the marine ecosystem and to humans. Different marine bacteria can participate in petroleum hydrocarbon degradation, and these bacteria are enriched in the presence of contaminants. This work was developed to study marine bacteria from different beaches in the state of Rio de Janeiro, evaluating their ability to tolerate and/or degrade polyaromatic hydrocarbons. For this, water samples were collected from eight beaches (Arpoador, Grumari, Urca, Sahy, Itacuruçá, Maricá, Búzios and Niterói) to construct microcosms in triplicate, with 0.1% naphthalene, a polyaromatic hydrocarbon model. The microcosms were incubated at room temperature and under agitation for 14 days, when 1 mL aliquots were obtained and submitted to serial dilutions (10-1 to 10-3) for sowing in Marine agar medium. The plates were incubated for 48-72 h at 35 °C, and a minimum of 30 colonies were isolated from each beach based on their morphology. To perform screening tests for emulsification and naphthalene degradation, the isolated strains were grown in Trypticase Soy Broth (TSB) at 35 °C for 48 h, and 1 mL of the growth was centrifuged for 15 min at 13,000 xg. The supernatant was added to 1 mL of hexadecane and vortexed for 2 minutes to determine the emulsification index after standing still for 24 h. The pellet was washed twice, using sterile 0.85% saline solution to perform the degradation test, using Bushnell Haas liquid medium supplemented with 3.5% sodium chloride (NaCl), and providing naphthalene as a carbon source. In addition, all isolated strains were identified by Sanger sequencing using the 515F primer (5'-GTGYCAGCMGCCGCGGTAA-3') and the BLAST tool from the National Center for Biotechnology Information (NCBI) was used for the analyzes, adopting a minimum of 98% coverage and 99% identity. Approximately 240 strains were isolated, among which 20 were preselected in the emulsification screening, and after growth optimization, emulsification indexes between 40 and 70% were obtained. Seventeen strains were considered positive for naphthalene degradation screening, as evaluated by the turbidity of the medium. Among the 240 strains, approximately 34 different genera were found, most of which were gram-negative. Some genera were specifically found on a beach (e.g., Frondibacter, found only on Arpoador beach). Other genera were found only on geographically close beaches (e.g., Marinobacter, found only in Itacuruçá and Sahy beaches). On the other hand, some genera were found on most of the studied beaches (e.g., Mesoflavibacter, Muricauda, Salipiger, Alteromonas and Celeribacter). All exemplified genera have already been reported in the literature for their ability to degrade polyaromatic hydrocarbons. These results show the distribution of bacterial groups capable of tolerating and/or participating in polyaromatic hydrocarbon degradation. It is important to highlight the presence of various groups on most of the beaches, especially because the samplings were performed under distinct geographic areas and seasonality. This makes them promising for application in remediation and monitoring studies of marine environments vulnerable to oil spills over the coast of Rio de Janeiro. Palavras-chave: degradation of hydrocarbons, emulsification, isolation, polyaromatic hydrocarbons Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) | |||||