Isolation of sulfate-reducing microorganisms from sediments in the geothermal area of Caviahue-Copahue (Argentina)

MARCELA HIPPERDINGER; EDGARDO DONATI; MICAELA GALLICET; MARÍA SOFÍA URBIETA; CAMILA SAFAR; CAMILA CASTRO

Simposio; 2nd International Symposium on Extreme Ecosystems and Extremophiles Organisms; 2019

Caviahue-Copahue geothermal area, located in Cordillera de Los Andes, in the Northwest of Neuquén province, Argentina, has a lot of different micro-environments which are constantly changing because of Copahue volcano?s activity. Different kinds of niches are found in that area involving neutral and acidic ones with moderate and extreme temperatures and aerobic or anaerobic conditions. These niches present a great diversity of microbes with potential biotechnological applications. Anaerobic environments of variable temperature are abundant in this area and their muds present a high retention of heavy metals. Sulfate-reducing microorganisms (SRM) are probably playing an important role in the biogeochemical processes of the zone. On this basis, the aim of the present study was the isolation of SRM representative of different geothermalsites of the Caviahue-Copahue system. For this purpose, muds from anaerobic pools and ponds with variable temperature (between 22º and 45º C) were sampled. Enrichment cultures and subsequent isolations were performed in order to allow the development of mesophilic and moderate thermophilic SRM. Natural muds were used as inoculum in modified Postgate B (PgB) liquid cultures supplemented with only 0,1% (w/v) of yeast extract to enhance the growth of SRM. Sequential dilutions were made from these enrichment cultures using the same medium. All cultures were incubated in anaerobic conditions at 30°C or 40°C depending on the original temperature of the site. Different dilutions of each sample weretransferred to PgB solid medium and incubated in the same conditions. Colonies which presented typical black iron sulfide precipitate (FeS) were used to inoculate PgB solid medium using streaking technique. Single colonies were sequentially transferred to liquid and solid cultures trying to achieve a pure culture for identification using 16S rRNA gene sequencing. Different kind of species of SRM were isolated and we are currently working on their genomic andphysiological characterization.