How flexible are the prokaryote consortia in the extreme habitat of the Copahue Geothermal system?

ZURAKOSKI N; GIAVENO, M. A.; ULLOA, R. J.; LAVALLE T; URBIETA M.S.; DONATI E.R.

Antofagasta

Simposio; 20 th International Biohidrometallurgy Symposium; 2013

The goal of these studies was to analize the metabolic flexibility developed by the prokaryotic microorganisms present in water and mud samples taken from the Copahue-Caviahue geothermal system (Neuquén, Argentina) when the growth conditions changed abruptly. The microbial consortia that colonize this extreme environment are mainly constituted by acidophilic and mesophilic, moderate and extreme thermophilic microorganisms, among others. These communities seem to have potential use in biotechnological applications such as bioleaching of metal sulphides. Samples were cultured at different temperatures, enrichment media and energy sources. The consortia response to these environmental changes was evaluated following the sulfur and iron oxidation kinetics. Molecular techniques such as DGGE (denaturing gel gradient electrophoresis) and FISH (fluorescent in situ hybridization) were carried out. The DGGE profiles allowed to evaluate the biodiversity and to make a cluster analysis using the Gel Compare software. The microbial communities were able to develop under all of the different conditions to which they were exposed; therefore these consortia can be considered flexible. The growth kinetics evidenced the consumption of the different energy sources, and the DGGE profiles indicated the selective enrichment of the microbial consortia. Diversity indexes such as the richness, the Simpson index, the Shannon-Weaver diversity index, and the Evenness index, were calculated. Finally, using a cluster analysis, it was possible to identify and get into groups the samples with similar profiles. That comparison was made studying the similarity between band patterns taken in pairs, using similarity coefficients such as Jaccard and the Pearson correlation coefficient. Results were displayed as similarity matrices and dendrograms. In a broad view, results showed that communities preferred to growth in conditions similar to those found in the environment of sampling sites. However, there were some species in all the tests that were able to be enriched even in conditions far away from those present in the sampling sites.