CONICET | Buscador de Institutos y Recursos Humanos

MI-P34 ARSENIC METABOLISM IN HIGH-ALTITUDE ANDEAN LAKES Stepanenko TM1 ; Soria MN1 ; Vignale FA1 ; Altabe SA2 ; Ordoñez OF2 ; Farías ME2 1 LIMLA-PROIMI-CONICET. 2 Laboratorio de Fisiología Microbiana-IBR-CONICET. E-mail: tatianamarielstepanenko@gmail.com The High-Altitude Andean Lakes (HAAL) consists of several shallow lakes located in a high-altitude desert of Central Andes region. In these lakes elevated concentrations of arsenic (As) were found in water, attributed mainly to volcanic activity. Diamante Lake is one of the most extreme environments within HAAL, due to its alkalinity (pH 11) and high As concentrations (234 mg/l). Given the high As content, arsenic metabolism was studied by metagenomics analysis of the Diamante Lake Red Haloarquea Biofilms (DLRB). All the genes necessary for the arsenic detoxifying mechanism (arsABC), arsenate respiration (arrBA) and arsenite oxidation (aioBA) were found in this study. To verify the importance of arsenic as a bioenergetic component, in this work we carried out physiological and molecular assays in the haloarqueaHalorubrum sp. DM2 (Euryarchaeota phylum) isolated from DLRB. The anaerobic and aerobic growth of this strain was determined by adding arsenic to the culture medium, arsenite (As III), as electron donor and arsenate (As V) as acceptor. We observed that in the presence of arsenate (As V) the anaerobic growth of Halorubrum sp. DM2 was greater with respect to the control. However, no growth differences were observed in aerobiosis. Moreover, results performed by RT-qPCR assays showed an increment in the transcriptional levels of the arsenic-related genes when arsenic was added to the growth medium. Although it is not yet possible to assign the underlying molecular mechanism, these results suggest that Halorubrum sp. DM2 is able to use arsenic as a bioenergetics substrate to maintain its growth.

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