Diatom floras were examined in a high-altitude geothermal field, 4200 -4500 m (29˚19'S 68˚W'), located in the Central Andean dry Puna ecoregion or southern Altiplano. These locations include hostile environments subjecting living organisms to extreme conditions. The aim of the present study was to investigate the spatial patterns and describe the response of diatom assemblages to differences in physical and chemical variables. Different shallow (<10 cm) aquatic systems with variable chemical and physical conditions (fumaroles, freshwater-saline rivers and swamps) were studied seasonally during 2011-2012. The conductivity exhibited high variability (360 to 18340 µS cm −1 ) among the systems studied, temperature was lower in rivers and swamps (6.8˚C -10˚C) and high in fumaroles stations (30˚C -37.5˚C), and pH was lower in fumaroles than freshwater systems (3.25 to 8.97). Statistical analyses suggest that the diatoms cluster into three major groups. The most common taxa include: Achnanthidium exiguum (Grunow) Czarnecki, Cocconeis placentula var. lineata (Ehrenberg) Van Heurck, Eolimna minima (Grunow) Lange-Bertalot, Staurosirella pinnata (Ehrenberg) Williams and Round, Navicula gregaria Donkin, Nitzschia inconspicua Grunow, Nitzschia palea (Kützing) Smith, Nitzschia perminuta (Grunow) Peragallo, and Planothidium lanceolatum (Brébisson ex Kützing) Lange-Bertalot. As expected, the 20 to 200 μm-size fraction contained the highest numbers of diatom taxa (53 species), although an unexpectedly high number (47 species) were also found in the smaller 5 to 20 μm-size fraction, more associated to fumaroles and saline systems. The 180 to 2000 μm size fraction contained only two species, including rosette-forming diatom Ulnaria ulna (Nitzsch) Compère, and the unicellular species Surirella chilensis Janisch, both species exclusively reported in freshwater systems. Canonical correspondence analysis (CCA) Other factors include substrate type, presence of macrophytes, current velocity and other local environmental conditions. The results presented here enhance our understanding of diatom richness/composition in hostile environments from a high-altitude arid and semi-arid geothermal region.

Strain ILE-2T was isolated from an upflow anaerobic sludge bed reactor treating brewery wastewater. The motile, non-sporulating, slightly curved cells (2–4×0.1 μm) stained Gram-negative and grew optimally at 42 °C and pH 7.1 with 0.5 % NaCl. The strain required yeast extract for growth and fermented Casamino acids, peptone, isoleucine, arginine, lysine, alanine, valine, glutamate, histidine, glutamine, methionine, malate, fumarate, glycerol and pyruvate to acetate, propionate and minor amounts of branched-chain fatty acids. Carbohydrates, formate, acetate, propionate, butyrate, isovalerate, methanol, ethanol, 1-propanol, butanol, lactate, succinate, starch, casein, gelatin, xylan and a number of other amino acids were not utilized. The DNA G+C content of strain ILE-2T was 52.7 mol%. 16S rRNA gene sequence analysis revealed that ILE-2T was distantly related to members of the genera Aminobacterium (83 % similarity) and Aminomonas (85 % similarity) in the family Syntrophomonadaceae, order Clostridiales, phylum Firmicutes. On the basis of the results of our polyphasic analysis, strain ILE-2T represents a novel species and genus within the family Syntrophomonadaceae, for which the name Aminiphilus circumscriptus gen. nov., sp. nov. is proposed. The type strain of Aminiphilus circumscriptus is ILE-2T (=DSM 16581T =JCM 14039T).

A thermophilic, sulfate-reducing bacterium, designated strain USBA-053T, was isolated from a terrestrial hot spring located at a height of 2500 m in the Colombian Andes (5° 45′ 33.29″ N 73° 6′ 49.89″ W), Colombia. Cells of strain USBA-053T were oval- to rod-shaped, Gram-negative and motile by means of a single polar flagellum. The strain grew autotrophically with H2 as the electron donor and heterotrophically on formate, propionate, butyrate, valerate, isovalerate, lactate, pyruvate, ethanol, glycerol, serine and hexadecanoic acid in the presence of sulfate as the terminal electron acceptor. The main end products from lactate degradation, in the presence of sulfate, were acetate, CO2 and H2S. Strain USBA-053T fermented pyruvate in the absence of sulfate and grew optimally at 57 °C (growth temperature ranged from 50 °C to 62 °C) and pH 6.8 (growth pH ranged from 5.7 to 7.7). The novel strain was slightly halophilic and grew in NaCl concentrations ranging from 5 to 30 g l−1, with an optimum at 25 g l−1 NaCl. Sulfate, thiosulfate and sulfite were used as electron acceptors, but not elemental sulfur, nitrate or nitrite. The G+C content of the genomic DNA was 56±1 mol%. 16S rRNA gene sequence analysis indicated that strain USBA-053T was a member of the class Deltaproteobacteria, with Desulfacinum hydrothermale MT-96T as the closest relative (93 % gene sequence similarity). On the basis of physiological characteristics and phylogenetic analysis, it is suggested that strain USBA-053T represents a new genus and novel species for which the name Desulfosoma caldarium gen. nov., sp. nov. is proposed. The type strain of the type species is USBA-053T ( = KCTC 5670T = DSM 22027T).

We studied the peptide-degrading anaerobic communities of methanogenic reactors from two mesophilic full-scale modified upflow anaerobic sludge blanket (UASB) reactors treating brewery wastewater in Colombia. Most probable number (MPN) counts varied between 7.1 x 10 8 and 6.6 x 10 9 bacteria/g volatile suspended solids VSS (Methanogenic Reactor 1) and 7.2 x 10 6 and 6.4 x 10 7 bacteria/g (VSS)(Methanogenic Reactor 2). Metabolites detected in the highest positive MPN dilutions in both reactors were mostly acetate, propionate, isovalerate and, in some cases, negligible concentrations of butyrate.Using the highest positive dilutions of MPN counts, 50 dominant strains were isolated from both reactors, and 12 strains were selected for sequencing their 16S rRNA gene based on their phenotypic characteristics.The small-subunit rRNA gene sequences indicated that these strains were affiliated to the families

S release of the protein into the extracellular medium. The substrate specificity range of the enzyme has been determined by drop test assays on PHA indicator slides containing biopolyesters of different side chain length.