Diversity and antimicrobial potential of bacteria isolated from Algarve caves

• Autor(a) principal: Veloso, Telma Luísa Machado
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/25453
• topic: Caves; Diversity; Bacteria; Antimicrobial activity

Recently, the need for new molecules with antimicrobial activity increased due to a continuous the increasing number of multi drug resistant pathogenic bacteria. To fill this urging need, the scientific community has made a great investment in searching for new microorganisms and their bioactive compounds. A great part of the effort has been focused in environments with extreme conditions, since in these environments the inhabiting microorganisms must have very particular features. Karstic caves are considered extreme environments due to the nutrient scarcity caused by absence of natural light that precludes the growth of vascular green plants. In addition, the relatively low and stable temperature and the high humidity levels, force cave dwelling microorganisms to become highly specialized. The fact that these unique habitats are poorly studied, in particular when considering the bacterial community, makes them a potential reservoir for both new species and new antimicrobial compounds, as demonstrated in the few existing studies. Considering these facts our study aimed at: i) obtain and identify bacterial isolates sampled in three caves of Algarve, namely Vale do Telheiro, Senhora and Ibne Ammar and, ii) assess their antimicrobial activity. From the collected samples of the three caves we are able to isolate 110 bacterial isolates. After sequencing and searching for homologies in the databases it was possible to include the isolates in phyla, namely Firmicutes, Proteobacteria and Actinobacteria, in a total of 19 genera. Regarding the antimicrobial activity, the tests were performed against six test agents: Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Aeromonas salmonicida ATCC 33658 and Bacillus cereus ATCC 14579. The results revealed that approximately 52% of the bacterial isolates presented antimicrobial activity against at least one test agent, and that ten bacterial isolates were able to inhibit the growth of more than four test agents. This study was the first to focus cultivable bacterial diversity in the Algarve caves and confirmed that prospection for new antimicrobial compounds in subterranean environments might be one of the strategies for fighting the problem of multi drug resistant bacteria.