Evaluation of the antimicrobial activity from Cerâmica Cave (Portugal) bactéria : the case study of Cupriavidus sp.

• Autor(a) principal: Gouveia, André Alexandre Grangeia
• 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/10773/25363
• topic: Cave systems; Cerâmica Cave; Bacteria; Antimicrobial activity; In vitro screening; Cupriavidus sp.,; Pigments; Culture media

Presently, the increasing number of multidrug resistant pathogens continues to be one of the major issues to be tackled by the scientific community. This is aggravated by the inability to find antibiotics with new chemical structures and/or modes of action. Therefore, the search for novel metabolites has expanded to the prospection of bacterial drug producer’s strains in extreme environments such as caves. Caves differ from surface environments in some of their core aspects, creating an extreme and unfavourable environment for microorganisms. The absence of light, high humidity and typical lack of nutrient input creates oligotrophic niches throughout the cave, with high potential for harbouring unique and unexplored microbial populations. Caves represent, thereby, a reservoir of unknown bacterial diversity potentially with antibiotic producing organisms. Additionally, few caves have been explored with the specific focus of finding these microorganisms. Taking this into consideration, this work focused on the antimicrobial activity of bacterial strains isolated from cave systems. The specific objectives of this work were: i) to review the methods used in the isolation of drug producer strains as well as in the evaluation of in vitro antibacterial activity ii) to identify and screen for antimicrobial activity bacterial strains isolated from Cerâmica Cave, Portugal; iii) to modulate the production of antimicrobial compounds and pigments by isolate CC166 (Cupriavidus sp.) and assess their bioactivity. An extensive review was made leading to the conclusion that caves may be one of the next most promising niches for novel drug producer bacterial strains. Among the isolation methods employed, the use of supplements, a wide variety of culture media and pre-treatments has been successfully applied in the isolation of drug producer strains. Based on the literature, the disk diffusion method and the agar well diffusion assay have been successfully employed on the screening for drug producer strains. Through the tackling of the second objective, antibiotic producer bacteria belonging to several genera were revealed. These included Streptomyces, Cupriavidus, Bacillus and Paenibacillus. Regarding the third objective, the employment of several culture media revealed remarkable patterns in the antimicrobial activity as well as in the modulation of pigments by Cupriavidus sp. CC166. Notably, Cupriavidus sp. CC166 was able to inhibit all pathogenic bacteria used as test agents in this work.