Resumo

Background: Sponges are sessile and filter feeders organisms which have 40 to 60% of the biomass comprised for microorganisms associated with. The present study aimed evaluate the biotechnological potential of the culturable bacteria associated with twelve species of marine sponges collected from a Brazilian coast. Materials and Methods: The specimens of sponges were collected (2005-2010) in the Cagarras Archipelago, Praia Vermelha Beach and Quadrado da Urca, Rio de Janeiro Coast, Brazil. Among 1,236 Colony Forming Units (CFU) associated with marine sponges, 116 morphologically different bacterial strains were analyzed in this study. These bacterial strains were evaluated for the ability to produce antibacterial substances, biofilm, biosurfactant and resistance to mercury and methylmercury. Also, it was made bioprospection assays for urease and phospholipase A2 production and for antibiotic resistance genes qnrA, qnrB, qnrS, tetM, tetO e tetL. Results and Discussion: Seventy one strains were able to produce biofilm, 15 were characterized as producers of antimicrobial substances and 21 produced biosurfactants. Also, 21 isolates were resistant to Hg, 15 of which were classified as highly resistant because they grew at 100 µM HgCl2. Fifteen resistant strains reduced Hg and presented merA gene in their genomes. The remaining six strains produced biosurfactants suggesting that may tolerate Hg by sequestrations. Eleven strains grew in presence of methylmercury (MeHg), two in media supplemented with 2.5 µM of MeHg, four with 10 µM, and five with 20 µM. Our results suggest a potential for mercury detoxification by marine sponges-associated resistant bacteria, either by its reduction or sequestration, as well as the possibility of bioremediation of toxic waste containing mercury. Thirty two strains were able to produce urease, 10 showed the presence of phoA gene and four of nine strains resistant to tetracycline or ciprofloxacin presented genes associated with resistance to these antibiotics. Conclusions: The results of this study point to the high biotechnological potential of bacteria associated with marine sponges. Studies like this are important to increase the information on these associated bacteria found off the coastline of Brazil, a place which has rich biodiversity that is still unknown. Financial Support: CAPES, FAPERJ, CNPq