Antibacterial activity of bacteria isolated from hydrothermal systems of Baja California Sur, Mexico

Background. Hydrothermal systems are a novel source for the discovery of new antimicrobial compounds and/or metabolites with biotechnological potential. Objectives. In the present research, a bioactivity screening of microorganisms isolated from shallow hydrothermal systems with the capacity to inhibit the growth of microorganisms of interest in human, aquaculture, and industrial health was carried out. Methods. Bacteria were isolated from two hydrothermal systems located in Bahía Concepción and other in El Sargento, B.C.S. in rainy and dry season. The antimicrobial activity against human pathogens, aquaculture pathogens, and marine biofilm-forming bacteria was evaluated, using the well diffusion technique. Results. 73 % of the isolated bacteria produced substances capable of inhibiting the growth of at least one of the microorganisms evaluated. Antagonism was only observed for 15 of the 36 target bacteria, Photobacterium damselae subsp. damselae was the most sensitive, which was inhibited by 51 % of the marine bacteria. Regarding the activity by site and season of collection, a greater number of active isolates against aquaculture pathogens was observed, predominating the dry season isolates for Mapachitos and Santispac, while in El Sargento the highest number of active isolates was obtained during the rainy season. Conclusion. Marine bacteria from hydrothermal systems are able to produce antimicrobial metabolites that could be used in different areas e.g. health and industry.