PROIMI   05436
PLANTA PILOTO DE PROCESOS INDUSTRIALES MICROBIOLOGICOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
HALOARCHAEA FROM THE ANDEAN PUNA: BIOLOGICAL ROLE IN THE ENERGY METABOLISM OF ARSENIC
Autor/es:
MARIA CECILIA RASUK; SORIA MARIANA N.; ORDOÑEZ OMAR F.; FARIAS MARIA EUGENIA
Lugar:
San Miguel de Tucumán
Reunión:
Congreso; XII CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE; 2017
Institución organizadora:
Sociedad Argentina de Microbiología
Resumen:
Arsenic metabolism is proposed to be an ancient mechanism in microbial life. In fact, some Bacteria and Archaea are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite as an electron donor. The high-altitude Andean lakes (HAAL) consist of several shallow lakes located in a high-altitude desert known as Puna, and these placed are distributed through Argentina, Chile, Bolivia, and Peru along the Central Andes region in South America. This environment host unexplored ecosystems of shallow lakes and salt flats at altitudes of 3700 meters above sea level (masl). In these places high concentrations of arsenic were found in the water, and this was attributed to the high Andean volcanism phenomenon which provides the geoenvironmental conditions and determine the availability of arsenic. Recently, our group has reported a metagenomics analysis of a microbialite from Diamante Lake, Catamarca, which was widely dominated by Archaea (96%), assigned to the class Halobacteria (commonly called as haloarchaea). Moreover, these authors strongly suggest that the prevalent haloarchaeal part of the biofilm have all the genes necessary for anaerobic arsenate respiration and arsenite oxidation, suggesting that these haloarchaea use arsenic compounds as bioenergetics substrates to sustain growth.The objective of our study was to investigate the presence and expression of genes (aioA and arrA) involved in obtaining energy from arsenic compounds in environmental samples and isolated strains. The effect of As [V] and As [III] during isolates growth and the possible role of As as bioenergetic substrate in two selected strains was also evaluated.The presence of aioA and arrA genes was confirmed in total community DNA from Diamante and Tebenquiche lakes, and the expression of these genes was confirmed by metatranscriptomic RNA samples, suggesting an active expression of both genes in the studied samples. Using selective isolation techniques, eighteen microorganisms belonging to the Halorubrum genera (phylum Euryarchaeota) were isolated. The genes enconding for aioA and arrA were detected in most of the isolates and their expression was verified in two selected strains. The physiological assays using a Chemically Defined Medium (CDM) showed a positive effect of As[III] and As[V] on cell growth. Moreover Halorubrum sp. DM2 was able to oxidize and reduce As. The confirmation of oxidation/reduction of arsenic and the transcriptional expression of these genes by RT-PCR in the strain DM2, support the previously raised hypothesis that the arsenic could be used in bioenergetics processes by the microorganisms inhabiting these environments.