PROIMI   05436
PLANTA PILOTO DE PROCESOS INDUSTRIALES MICROBIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Characterization of bacteria isolated from pristine High Altitude Andean Wetlands resistant to extreme environmental conditions
Autor/es:
ORDOÑEZ, OMAR; FLORES, MARÍA REGINA; DIB, JULIÁN RAFAEL; FERNANDEZ ZENOFF, MARÍA VERÓNICA; FARÍAS, MARIA EUGENIA
Lugar:
Rosario
Reunión:
Congreso; V Congreso Argentino de Microbiología General; 2008
Resumen:
High Altitude Andean Wetlands (HAAW) is a system of shallow oligotrophic lakes originated in the tertiary age distributed across The Puna, the high plateau of the South American Andes from Bolivia to Argentina. These lakes are scattered throughout the region at altitudes from 3,600 to 4,600 meters. Microbial communities within these aquatic ecosystems are tolerant to wide fluctuations of environmental factors in addition to steady-state extreme conditions such as high UV radiation (maxim UV-B W/m2 in situ 10,78), high heavy metal content (mainly arsenic 0,8 to 11,8 mg/L), high salinity (0,4 to 117 ppm), oligotrophic and low phosphorus (i.e. 0,02 mg/L).HAAW ecosystems are totally unexplored with no access roads, which provide an unique opportunity to study the ecosystem interactions and responses to environmental stress. Salar de la Laguna Verde is a system of four oligotrophic shallow lakes (L.) (L. Aparejos, L. Azul, L. Negra and L. Verde) distributed along 100 km2. L. Catal belongs to Salar del Hombre Muerto in Catamarca and L. Vilama is located in Jujuy. The exploration at the microbial diversity of HAAW could give new insights to the mechanism of adaptation and tolerance to extreme environments.Aim: The aim of this work was to isolate bacteria from different wetlands and to study the diverse response to UV-B and antibiotics resistance of isolated microorganisms. Experimental Design: Water and sediment samples were exposed to UV-B radiation at similar doses than natural environmental conditions. Most resistant bacteria were isolated by their intrinsic resistances to UV-B, salinity and antibiotics resistances. All of them have been identified by 16S rDNA sequence. To study UV-B resistance, the microorganisms were grown in adequate medium at 30 ºC in flask with constant agitation. The cells were harvested at exponential phase. Pellets were washed in 0.9 % NaCl and fractions of each cell suspension were transferred to sterile quartz tubes. Tubes were exposed under UV-B lamps and radiation doses were quantified by a radiometer. Survival percentages were determinated by colony forming units at different expositions times.The antibiotic resistance was determitated by disk diffusion methods on Mǘeler-Hilton agar according to the current recommendations of the National Committee for Clinical laboratory Standards (NCCLS) for susceptibility.Results: Until this moment we have isolated 155 strains distributed in the following taxonomic groups: Gamma, Beta, Alpha-proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and Archaea. These results showed a prevalence of Firmicutes (43%) and Gamma-proteobacteria (32%). We established the presence and correlation of resistances to UV-B radiation and antibiotics in Andean wetlands and that wetland water and sediments in these environments are a source of antibiotic resistant bacteria.