PROBIEN   20416
INSTITUTO DE INVESTIGACION Y DESARROLLO EN INGENIERIA DE PROCESOS, BIOTECNOLOGIA Y ENERGIAS ALTERNATIVAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Nitrifying communities enriched from geothermal springs in Argentina
Autor/es:
WENDT, K.; DONATI, E; A. GIAVENO; SPIECK, E.
Lugar:
Bonn
Reunión:
Workshop; for General and Applied Microbiology (VAAM); 2011
Institución organizadora:
Universidad de Bonn
Resumen:
Nitrification involves the sequential oxidation of ammonia to nitrite and further to nitrate. Two physiological groups of chemolithoautotrophic microorganisms, which perform this process, are referred to as ammonia-oxidizing bacteria or archaea (AOB and AOA) and nitrite-oxidizing bacteria (NOB). Nitrification plays a significant role in the global nitrogen cycle and occurs in a varity of moderate and extreme environments, including hot springs. Sampling was performed in Las Máquinas, a thermal spring in the Argentinean province Neuquén in 2007-2009. This extreme habitat is dominated by the volcano Copahue and the surrounding geothermal area, which has not been investigated in detail in biological terms. The sampling sites are characterized through mud puddles with temperatures from 37°C to 74°C, pH values from acidic (2.5) to the neutral range as well as sulfur deposits. Despite the fastidious growth and protracted cultivation of nitrifiers, we successfully enriched ammonia- and nitrite-oxidizing microorganism from Las Máquinas at moderate (28°C) and thermophilic (70°C) conditions. Using 28°C for cultivation, members of Nitrospira, the dominant nitrite oxidizer at moderate thermophilic conditions [1], were detected by PCR with specific primers and typical cells of Nitrosomonas were found via electron microscopy. First fluorescence in-situ hybridization experiments showed the coexistence of bacteria and archaea in the same AOB or NOB culture. Analyses of the 16S rRNA genes confirmed the FISH results in the case of the NOB culture and revealed the occurrence of archaeal und bacterial ammonia monooxygenase genes (amoA), a subunit of the key enzyme of aerobic ammonia oxidation. Currently, both AOB and NOB enrichments at 70°C show a very slow consumption of the admitted substrate and cells are resistant against disruption. Therefore, identification and characterization of the potential novel nitrifiers still remain tricky. However, further investigations will gain insight into nitrification in such exclusive locations and the composition of the nitrifying community. [1] Lebedeva et al., 2010, FEMS Microbiol. Ecol, in press