Antimicrobial activity and resistance to UV-light by pigmented soil bacteria from Whalers Bay, Deception Island, Maritime Antarctica

Microorganisms from the Antarctic continent have attracted attention due to their ability to produce bioactive secondary metabolites at low temperatures. The search for pigmented compounds produced by microbial strains from cold environments has been investigated due to their applications in the cosmetics and pharmaceutical industries. This study evaluated the resistance to UV-C (254 nm) light and antimicrobial activity of pigments produced by soil bacteria from Deception Island, Antarctica. Ten pigmented bacteria were isolated and subjected to an assay for resistance to ultraviolet (UV) radiation. All strains showed resistance. However, six, five, and five strains were able to survive after 10, 15, and 30 minutes of light exposure. UV-resistant strains UVBACD.10 and Brachybacterium paraconglomeratum UVBACD.5 were selected for the minimum inhibitory concentration (MIC) assay against pathogenic bacteria. UVBACD.5 showed inhibitory effects on the pathogenic bacteria tested at different concentration levels, assayed in triplicate. The best antimicrobial activity reached a MIC of 0.021 mg mL-1 against Escherichia coli. Soil from Whalers Bay can be considered a source of microorganisms of industrial biotechnological interest. The results of this work encourage studies on the characterization and purification of secondary metabolites produced by isolates from the Antarctic continent for future applications in the pharmaceutical and cosmetic areas.