Physiologic versatility and growth flexibility as the main characteristics of a novel thermoacidophilic Acidianus isolated from Copahue geothermal area in Argentina

GIAVENO, M. A.; URBIETA, M. S.; ULLOA, R. J.; GONZALEZ TORIL, E.; DONATI, E

MICROBIAL ECOLOGY

SPRINGER

Lugar: Berlin; Año: 2013 vol. 65 p. 336 - 346

0095-3628

A novel species of archaea has been isolated in pure culture from various geothermal acidic hot springs in Copahue, Argentina. One of the most striking characteristic of this isolate, that we have called ALE1, is its amazing metabolic versatility. It has proven able to grow on sulphur, tetrathionate, iron (II) and sucrose under aerobic conditions, but it can also develop under anaerobic conditions using ferric iron or sulphur as electron acceptors and sulphur or hydrogen as electron donors autotrophically. Temperature of 75 ºC and pH between 2.5 and 3.0 are ALE1 strain optimal growth conditions, however cells are able to oxidise iron (II) even at pH 1.0. This thermoacidophilic archaeon has an irregularly coccus-shaped form surrounded by a regularly arrayed glycoprotein layer (S-layer). Phylogenetic analysis shows that ALE1 strain belongs to Sulfolobaceae family in the Thermoprotei class, within the Crenarchaeota phylum. Based on 16S rRNA gene sequence similarity on NCBI data base, ALE1 does not have very close related sequences reported, cultured or, which is more surprising, uncultured. Its closest related species are strains of Acidianus hospitalis (91 % of sequence similarity), Acidianus infernus (90 %), Acidianus ambivalens (90 %) and Acidianus manzanensis (90 %). Its DNA base composition of 34.5% mol C+G is higher than reported for other Acidianus species. Considering all these extraordinary physiological and phylogenetic characteristics of ALE1 strain, we considered it to represent a novel species of the genus Acidianus and we propose to name it Acidianus copahuensis. The aim of this study is to characterise physiologically this novel archaeal isolation in order to understand its role in iron and sulphur geochemical cycles in Copahue geothermal area and to evaluate its potential applications in diverse bioprocesses, in particular, bioleaching and biooxidation.