title: Diverse UV-B resistance of culturable bacterial community from high-altitude wetland water.
abstract: 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.
authors.affiliation: PROIMI Planta Piloto de Procesos Industriales Microbiológicos, Tucumán, Argentina.
authors.forename: Veronica Fernández
authors.initials: VF
authors.lastname: Zenoff
authors.forename: Judith
authors.initials: J
authors.lastname: Heredia
authors.forename: Marcela
authors.initials: M
authors.lastname: Ferrero
authors.forename: Faustino
authors.initials: F
authors.lastname: Siñeriz
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Farías
mesh_terms: D000150:Acinetobacter / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D000531:Altitude; D003470:Culture Media; D017753:Ecosystem; D005618:Fresh Water / Q000382:microbiology*; D006094:Gram-Positive Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*; D008969:Molecular Sequence Data; D010860:Pigments, Biological / Q000378:metabolism; D011836:Radiation Tolerance; D017422:Sequence Analysis, DNA; D014466:Ultraviolet Rays
chemical_list: D003470:Culture Media; D010860:Pigments, Biological