Diverse UV-B resistance of culturable bacterial community from high altitude wetland water”

FERNÁNDEZ ZENOFF, VERONICA.; HEREDIA, JUDITH; FERRERO, MARCELA; SIÑERIZ, FAUSTINO; FARÌAS, MARÌA EUGENIA

CURRENT MICROBIOLOGY

Springer International

Año: 2006 vol. 52 p. 359 - 362

0343-8651

PROIMI Planta Piloto de Procesos Industriales Microbiologicos, Tucuman, Argentina. Isolation of most ultraviolet B (UV-B)-resistant culturable bacteria that occur in the habitat of Laguna Azul, a high-altitude wetland [4554 m above sea level (asl)] from the Northwestern Argentinean Andes, was carried out by culture-based methods. Water from this environment was exposed to UV-B radiation under laboratory conditions during 36 h, at an irradiance of 4.94 W/m2. It was found that the total number of bacteria in water samples decreased; however, most of the community survived long-term irradiation (312 nm) (53.3 kJ/m2). The percentage of bacteria belonging to dominant species did not vary significantly, depending on the number of UV irradiation doses. The most resistant microbes in the culturable community were Gram-positive pigmented species (Bacillus megaterium [endospores and/or vegetative cells], Staphylococcus saprophyticus, and Nocardia sp.). Only one Gram-negative bacterium could be cultivated (Acinetobacter johnsonii). Nocardia sp. that survived doses of 3201 kJ/m2 were the most resistant bacteria to UV-B treatment. This study is the first report on UV-B resistance of a microbial community isolated from high-altitude extreme environments, and proposes a method for direct isolation of UV-B-resistant bacteria from extreme irradiated environments.