Arsenic metabolism in high-altitude Andean Lakes

STEPANENKO TATIANA MARIEL; ALTABE SILVIA; SORIA MARIANA NOELIA; ORDOÑEZ OMAR; VIGNALE FEDERICO; FARIAS MARIA EUGENIA

Parana, Entre Rios

Congreso; LIV Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2018

SAIB

The High-Altitude Andean Lakes (HAAL) consists of several shallow lakes located in a high-altitude desert of Central Andes region. In theselakes elevated concentrations of arsenic (As) were found in water, attributed mainly to volcanic activity. Diamante Lake is one of the mostextreme environments within HAAL, due to its alkalinity (pH 11) and high As concentrations (234 mg/L). Given the high As content, arsenicmetabolism was studied by metagenomics analysis of the Diamante Lake Red Haloarquea Biofilms (DLRB). All the genes necessary for thearsenic detoxifying mechanism (arsABC), arsenate respiration (arrBA) and arsenite oxidation (aioBA) were found in this study. To verify theimportance of arsenic as a bioenergetic component, in this work we carried out physiological and molecular assays in the haloarqueaHalorubrumsp. DM2 (Euryarchaeota phylum) isolated from DLRB. The anaerobic and aerobic growth of this strain was determined by adding arsenic to theculture medium, arsenite (As III), as electron donor and arsenate (As V) as acceptor. We observed that in the presence of arsenate (As V) theanaerobic growth of Halorubrumsp. 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 wasadded to the growth medium. Although it is not yet possible to assign the underlying molecular mechanism, these results suggest thatHalorubrumsp. DM2 is able to use arsenic as a bioenergetics substrate to maintain its growth.