Search

Studies of thermophilic microorganisms have shown that they have a considerable biotechnological potential due to their optimum growth and metabolism at high temperatures. Thermophilic archaea have unique characteristics with important biotechnological applications, many of these species could be used in bioleaching processes to recover valuable metals from mineral ores. Particularly, bioleaching at high temperatures using thermoacidophilic microorganisms can greatly improve metal solubilization from refractory mineral species such as chalcopyrite (CuFeS2), one of the most abundant and widespread copper-bearing minerals. Interfacial processes such as early cell adhesion, biofilm development, and the formation of passive layers on the mineral surface play important roles in the initial steps of bioleaching processes. The present work focused on the investigation of different bioleaching conditions using the thermoacidophilic archaeon Acidianus copahuensis DSM 29038 to elucidate which steps are pivotal during the chalcopyrite bioleaching. Fluorescent in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) were used to visualize the microorganism&ndash, mineral interaction. Results showed that up to 85% of copper recovery from chalcopyrite could be achieved using A. copahuensis. Improvements in these yields are intimately related to an early contact between cells and the mineral surface. On the other hand, surface coverage by inactivated cells as well as precipitates significantly reduced copper recoveries.

The study of microbial communities from extreme environments is a fascinating topic. With every study, biologists and ecologists reveal interesting facts and questions that dispel the old belief that these are inhospitable environments. In this work, we assess the microbial diversity of three hot springs from Neuqu&eacute, n, Argentina, using high-throughput amplicon sequencing. We predicted a distinct metabolic profile in the acidic and the circumneutral samples, with the first ones being dominated by chemolithotrophs and the second ones by chemoheterotrophs. Then, we collected data of the microbial communities of hot springs around the world in an effort to comprehend the roles of pH and temperature as shaping factors. Interestingly, there was a covariation between both parameters and the phylogenetic distance between communities, however, neither of them could explain much of the microbial profile in an ordination model. Moreover, there was no correlation between alpha diversity and these parameters. Therefore, the microbial communities&rsquo, profile seemed to have complex shaping factors beyond pH and temperature. Lastly, we looked for taxa associated with different environmental conditions. Several such taxa were found. For example, Hydrogenobaculum was frequently present in acidic springs, as was the Sulfolobaceae family, on the other hand, Candidatus Hydrothermae phylum was strongly associated with circumneutral conditions. Interestingly, some singularities related to sites featuring certain taxa were also observed.

Geothermal areas are the niches of a rich microbial diversity that is not only part of the intangible patrimony of a country but also the source of many microbial species with potential biotechnological applications. Particularly, microbial species in geothermal areas in Argentina have been scarcely explored regarding their possible biotechnological uses. The purpose of this work was to explore the proteolytic and keratinolytic enzymatic potential of microorganisms that inhabit in the Domuyo geothermal area in the Neuquén Province. To this end, we did enrichment cultures from two high-temperature natural samples in mineral media only supplemented with whole chicken feathers. After the isolation and the phylogenetic and morphologic characterization of different colonies, we obtained a collection of Bacillus cytotoxicus isolates, a species with no previous report of keratinolytic activity and only reported in rehydrated meals connected with food poisoning outbreaks. Its natural habitat has been unknown up to now. We characterized the proteolytic and keratinolytic capacities of the B. cytotoxicus isolates in different conditions, which proved to be remarkably high compared with those of other similar species. Thus, our work represents the first report of the isolation as well as the keratinolytic capacity characterization of strains of B. cytotixicus obtained from a natural environment., Centro de Investigación y Desarrollo en Fermentaciones Industriales

The Copahue volcano-R&iacute, o Agrio system, on Patagonia Argentina, comprises the naturally acidic river R&iacute, o Agrio, that runs from a few meters down the Copahue volcano crater to more than 40 km maintaining low pH waters, and the acidic lagoon that sporadically forms on the crater of the volcano, which is studied for the first time in this work. We used next-generation sequencing of the 16S rRNA gene of the entire prokaryotic community to study the biodiversity of this poorly explored extreme environment. The correlation of the operational taxonomic units (OTUs)s presence with physicochemical variables showed that the system contains three distinct environments: the crater lagoon, the Upper R&iacute, o Agrio, and the Salto del Agrio waterfall, a point located approximately 12 km down the origin of the river, after it emerges from the Caviahue lake. The prokaryotic community of the Copahue Volcano-R&iacute, o Agrio system is mainly formed by acidic bacteria and archaea, such as Acidithiobacillus, Ferroplasma, and Leptospirillum, which have been isolated from similar environments around the world. These results support the idea of a ubiquitous acidic biodiversity, however, this highly interesting extreme environment also has apparently autochthonous species such as Sulfuriferula, Acidianus copahuensis, and strains of Acidibacillus and Alicyclobacillus.

The geothermal Copahue-Caviahue (GCC) system (Argentina) is an extreme acidic environment, dominated by the activity of Copahue volcano. Environments characterised by low pH values, such as volcanic areas, are of particular interest for the search of acidophilic microorganisms with application in biotechnological processes. In this work, sulfate-reducing microorganisms were investigated in geothermal acidic, anaerobic zones from GCC system. Sediment samples from Agua del Limón (AL1), Las Máquinas (LMa2), Las Maquinitas (LMi) and Baño 9 (B9–2, B9–3) were found to be acidic (pH values 2.1–3.0) to moderate acidic (5.1–5.2), containing small total organic carbon values, and ferric iron precipitates. The organic electron donor added to the enrichment was completely oxidised to CO2. Bacteria related to ‘Desulfobacillus acidavidus’ strain CL4 were found to be dominant (67–83% of the total number of clones) in the enrichment cultures, and their presence was confirmed by their isolation on overlay plates. Other bacteria were also detected with lower abundance (6–20% of the total number of clones), with representatives of the genera Acidithiobacillus, Sulfobacillus, Alicyclobacillus and Athalassotoga/Mesoaciditoga. These enrichment and isolates found at low pH confirm the presence of anaerobic activities in the acidic sediments from the geothermal Copahue-Caviahue system. Fil: Willis, Graciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Nancucheo, Ivan. Universidad San Sebastian.; Chile Fil: Hedrich, Sabrina. Federal Institute for Geosciences and Natural Resources; Alemania Fil: Giaveno, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Johnson, David Barrie. Bangor University; Reino Unido

Ultraviolet-A (UVA) radiation is one of the most stressful oxidative agents that bacteria have to face in natural environments. The effect of this radiation on growth, survival, biofilm formation, and bioleaching activity of two Leptospirillum ferrooxidans strains was studied, comparing the collection strain DSM2705 with FAM-RA2, a strain recently isolated from Famatina (La Rioja, Argentina), at 3869 m above sea level (ma.s.l.). We demonstrated that the isolate FAM-RA2 was more UVA resistant than the collection strain DSM2705 in kinetic growth and biofilm formation assays. However, both strains presented a similar behavior in their bioleaching capacity. Higher levels of intracellular reactive oxygen species (ROS) after UVA exposure were detected in DSM2705 strain, suggesting the presence of stronger defensive mechanisms against oxidative stress in FAM-RA2 strain. Assays of biofilm formation showed that UVA radiation induced cell adhesion and extracellular polymeric substance (EPS) production in the collection strain DSM2705, but not in the FAM-RA2 strain. The ability of UVA radiation to increase biofilm formation in DSM2705 led us to suppose that this agent could promote its bioleaching activity; however, under these studied conditions, this stress agent did not enhance metal sulfide dissolution. This study provides first insights into the effects of UVA radiation on the physiological features of acidophilic microorganisms.

Metal pollution is a great concern worldwide and the development of new technologies for more sustainable extraction methods as well as for the remediation of polluted sites is essential. Extremophilic microorganisms are attractive for this purpose since they have poly-resistance mechanisms which make them versatile. In this work, we sampled an acidic river and a hot spring of Caviahue-Copahue volcanic environment. The indigenous microbial communities were exposed to five heavy metals (Cd, Co, Cu, Ni and Zn) in batch-cultures favouring different metabolisms of biotechnological interest. Remarkably, high tolerance values were reached in all the cultures, even though most of the metals studied were not present in the environmental sample. Particularly, outstanding tolerances were exhibited by acidophiles, which grew at concentrations as high as 400 mM of Zn and Ni. High-throughput amplicon sequencing of 16S rRNA gene was used to study the indigenous communities and the resistant consortia. We took three approaches for the analysis: phylotypes, OTUs and amplicon sequence variants (ASVs). Interestingly, similar conclusions were drawn in all three cases. Analysing the phylogenetic structure and functional potential of the adapted consortia, we found that the strongest selection was exerted by the culture media. Notably, there was a poor correlation between alpha diversity and metal stress; furthermore, metal stress did not seem to harm the functional potential of the consortia. All these results reveal a great adaptability and versatility. At the end, 25 metal-resistant extremophilic consortia with potential uses in bioremediation, bioleaching or biomonitoring processes were obtained.

The understanding of biofilm formation by bioleaching microorganisms is of great importance for influencing mineral dissolution rates and to prevent acid mine drainage (AMD). Thermo-acidophilic archaea such as Acidianus, Sulfolobus and Metallosphaera are of special interest due to their ability to perform leaching at high temperatures, thereby enhancing leaching rates. In this work, leaching experiments and visualization by microscopy of cell attachment and biofilm formation patterns of the crenarchaeotes Sulfolobus metallicus DSM 6482(T) and the Acidianus isolates DSM 29038 and DSM 29099 in pure and mixed cultures on sulfur or pyrite were studied. Confocal laser scanning microscopy (CLSM) combined with fluorescent dyes as well as fluorescently labeled lectins were used to visualize different components (e.g. DNA, proteins or glycoconjugates) of the aforementioned species. The data indicate that cell attachment and the subsequently formed biofilms were species- and substrate-dependent. Pyrite leaching experiments coupled with pre-colonization and further inoculation with a second species suggest that both species may negatively influence each other during pyrite leaching with respect to initial attachment and pyrite dissolution rates. In addition, the investigation of binary biofilms on pyrite showed that both species were heterogeneously distributed on pyrite surfaces in the form of individual cells or microcolonies. Physical contact between the two species seems to occur, as revealed by specific lectins able to specifically bind single species within mixed cultures.

Although arsenic (As) is recognized as a toxic element for living species, some microorganisms have the ability to tolerate and transform it; recent studies have proposed to take advantage of such capacity to develop sustainable bioremediation strategies. In this study, we evaluated the adaptation to increasing concentrations of As(III) and As(V) of three metabolically different microbial cultures (heterotrophic, autotrophic–acidophilic, and anaerobic) obtained from a sample with low‐soluble As content from the Copahue geothermal system. At the end of the adaptation process, the heterotrophic culture was able to grow at 20 mM and 450 mM of As(III) and As(V), respectively; the autotrophic– acidophilic culture showed tolerance to 15 mM of As(III) and 150 mM of As(V), whereas the anaerobic culture only developed in As(V) at concentrations up to 50 mM. The most tolerant consortia were characterized by their growth performance, complexity, and the presence of genes related to As metabolism and resistance. Regarding the consortia complexity, the predominant genera identified were: Paenibacillus in both heterotrophic consortia, Acidithiobacillus in the autotrophic–acidophilic consortium tolerant to As(III), Acidiphilium in the autotrophic–acidophilic consortium tolerant to As(V), and Thiomonas and Clostridium in the anaerobic consortium. This study is the first report of As tolerance microorganisms obtained from Copahue and reasserts the versatility and flexibility of the community of this natural extreme environment; also, it opens the door to the study of possible uses of these consortia in the design of biotechnological processes where the As concentration may fluctuate. Fil: Lima, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

Thermophilic aerobic bacteria were isolated from two geothermal areas in Neuquén province using two different enrichment methods and a total of 30 isolates were obtained. From chicken feather enrichment cultures, strains affiliated to Bacillus cytotoxicus and Bacillus licheniformis were isolated and all of them demonstrated the capability to degrade completely chicken feather. A preliminary research on biotechnological enzymes’ potential demonstrated that all the isolates displayed at least one of the extracellular hydrolytic enzymes tested. Most of the isolates showed protease, inulinase and/or pectinase activities, while cellulase and xylanase activities were less common. In light of these findings, geothermal areas of Argentina may be considered as a potential source of thermophilic bacteria able to produce many industrially relevant enzymes., Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales

Background: Several archaeal species from the order Sulfolobales are interesting from the biotechnological point of view due to their biomining capacities. Within this group, the genus Acidianus contains four biomining species (from ten known Acidianus species), but none of these have their genome sequenced. To get insights into the genetic potential and metabolic pathways involved in the biomining activity of this group, we sequenced the genome of Acidianus copahuensis ALE1 strain, a novel thermoacidophilic crenarchaeon (optimum growth: 75 °C, pH 3) isolated from the volcanic geothermal area of Copahue at Neuquén province in Argentina. Previous experimental characterization of A. copahuensis revealed a high biomining potential, exhibited as high oxidation activity of sulfur and sulfur compounds, ferrous iron and sulfide minerals (e.g.: pyrite). This strain is also autotrophic and tolerant to heavy metals, thus, it can grow under adverse conditions for most forms of life with a low nutrient demand, conditions that are commonly found in mining environments. Results: In this work we analyzed the genome of Acidianus copahuensis and describe the genetic pathways involved in biomining processes. We identified the enzymes that are most likely involved in growth on sulfur and ferrous iron oxidation as well as those involved in autotrophic carbon fixation. We also found that A. copahuensis genome gathers different features that are only present in particular lineages or species from the order Sulfolobales, some of which are involved in biomining. We found that although most of its genes (81%) were found in at least one other Sulfolobales species, it is not specifically closer to any particular species (60-70% of proteins shared with each of them). Although almost one fifth of A. copahuensis proteins are not found in any other Sulfolobales species, most of them corresponded to hypothetical proteins from uncharacterized metabolisms. Conclusion: In this work we identified the genes responsible for the biomining metabolisms that we have previously observed experimentally. We provide a landscape of the metabolic potentials of this strain in the context of Sulfolobales and propose various pathways and cellular processes not yet fully understood that can use A. copahuensis as an experimental model to further understand the fascinating biology of thermoacidophilic biomining archaea., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Malaysia has a great number of hot springs, especially along the flank of the Banjaran Titiwangsa mountain range. Biological studies of the Malaysian hot springs are rare because of the lack of comprehensive information on their microbial communities. In this study, we report a cultivation-independent census to describe microbial communities in six hot springs. The Ulu Slim (US), Sungai Klah (SK), Dusun Tua (DT), Sungai Serai (SS), Semenyih (SE), and Ayer Hangat (AH) hot springs exhibit circumneutral pH with temperatures ranging from 43°C to 90°C. Genomic DNA was extracted from environmental samples and the V3-V4 hypervariable regions of 16S rRNA genes were amplified, sequenced, and analyzed. High-throughput sequencing analysis showed that microbial richness was high in all samples as indicated by the detection of 6,334-26,244 operational taxonomy units. In total, 59, 61, 72, 73, 65, and 52 bacterial phyla were identified in the US, SK, DT, SS, SE, and AH hot springs, respectively. Generally, Firmicutes and Proteobacteria dominated the bacterial communities in all hot springs. Archaeal communities mainly consisted of Crenarchaeota, Euryarchaeota, and Parvarchaeota. In beta diversity analysis, the hot spring microbial memberships were clustered primarily on the basis of temperature and salinity. Canonical correlation analysis to assess the relationship between the microbial communities and physicochemical variables revealed that diversity patterns were best explained by a combination of physicochemical variables, rather than by individual abiotic variables such as temperature and salinity., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Thermophilic Archaea and Bacteria occupy heated environments. Advancement of next-generation sequencing (NGS), single-cell analyses, and combinations of –omics and microscopic technologies have resulted in the discovery of new thermophiles. This e-book consists of a review, and 10 original articles authored by 94 authors. The main aim of this Research Topic of Frontiers in Microbiology was to provide a platform for researchers to describe recent findings on the ecology of thermophiles using NGS, functional genomics, comparative genomics, gene evolution, and extremozyme discovery.

Biomining is an applied biotechnology for mineral processing and metal extraction from ores and concentrates. This alternative technology for recovering metals involves the hydrometallurgical processes known as bioleaching and biooxidation where the metal is directly solubilized or released from the matrix for further solubilization, respectively. Several commercial applications of biomining can be found around the world to recover mainly copper and gold but also other metals; most of them are operating at temperatures below 40–50 °C using mesophilic and moderate thermophilic microorganisms. Although biomining offers an economically viable and cleaner option, its share of the world´s production of metals has not grown as much as it was expected, mainly considering that due to environmental restrictions in many countries smelting and roasting technologies are being eliminated. The slow rate of biomining processes is for sure the main reason of their poor implementation. In this scenario the use of thermophiles could be advantageous because higher operational temperature would increase the rate of the process and in addition it would eliminate the energy input for cooling the system (bioleaching reactions are exothermic causing a serious temperature increase in bioreactors and inside heaps that adversely affects most of the mesophilic microorganisms) and it would decrease the passivation of mineral surfaces. In the last few years many thermophilic bacteria and archaea have been isolated, characterized, and even used for extracting metals. This paper reviews the current status of biomining using thermophiles, describes the main characteristics of thermophilic biominers and discusses the future for this biotechnology. Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Castro, Camila Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

Toxic metal soil pollution is one of the most serious environmental problems, with phytoextraction being an ecological and inexpensive potential solution to recuperate soil functionality. This emergent technology has produced good results for many elements, but phytoextraction has not been as successful for lead as for other pollutants. This research aimed to evaluate several factors that could be determinant on Pb uptake by the accumulator plants Bidens pilosa and Tagetes minuta. Topsoils (bulk and ryzospheric) and plants were collected around a former Pb smelter, and sequential extractions of Pb, Cu and Zn, organic matter content, electrical conductivity, pH, and texture were measured in soils. Also, bacterial diversity in soil was determined by the denaturing gradient gel electrophoresis (DGGE) technique. The Pb, Cu, and Zn concentrations in soil extractions and plants (leaves, stem, and root) were quantified by T-XRF in Synchrotron, Brazil. Our results demonstrated that Pb uptake from polluted soils and translocation to aerial tissues by two Asteraceae species are related not only to the traditional soil parameters, but even more importantly to the Zn and Cu concentrations in plant and soils. In addition, the soil bacterial biodiversity also affects the Pb uptake by plants. In this study, we propose the total translocation factor (TTF) to evaluate the phytoextraction efficiency, which is given by the ratio of total extraction of Pb in aerial organs and roots, instead of using the Pb concentrations alone. Fil: Salazar, María Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Rodriguez, Judith Hebelen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Vergara Cid, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Bernardelli, Cecilia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Pignata, Maria Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Desulfotomaculum copahuensis strain CINDEFI1 is a novel spore-forming sulfate-reducing bacterium isolated from the Copahue volcano area, Argentina. Here, we present its draft genome in which we found genes related with the anaerobic respiration of sulfur compounds similar to those present in the Copahue environment., Centro de Investigación y Desarrollo en Fermentaciones Industriales

Two brown algae, Macrocystis pyrifera and Undaria pinnatifida, were employed to remove Cr(III) from aqueous solutions. Both seaweeds were characterized in terms of alginate yields. The alginate contents were 20 and 30% of the dry weight for M. pyrifera and U. pinnatifida, respectively. Kinetics experiments were carried out at different initial pH values. Cr(III) biosorption was affected by the solution pH. The highest metal uptake was found at pH 4 for both biosorbents. Different models were applied to elucidate the rate-controlling mechanism: pseudo-first-order, pseudo-second-order, external mass transfer and intra-particle diffusion. The application of Langmuir, Freundlich and Dubinin-Radushkevich models to the equilibrium data showed a better fitting to the first model. The maximum Cr(III) sorption capacity (q m) and the affinity coefficient (b) were very similar for both biosorbents: 0.77mmol/g and 1.20L/mmol for M. pyrifera and 0.74mmol/g and 1.06L/mmol for U. pinnatifida. The free energy of the sorption process was estimated using the Dubinin-Radushkevich isotherm. The values indicate that the processes are chemical sorptions. To evaluate the significance of the ion-exchange mechanism, the light metals (Ca 2+, Na +, Mg 2+ and K +) and pH were measured during the experiments. Fil: Plaza Cazón, Josefina del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Benitez, Leonardo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Viera, Marisa Rosana. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

This study investigated the adsorption of Hg(II) on Macrocystis pyrifera and Undaria pinnatifida in monometallic system in the presence of Zn(II), Cd(II) and Ni(II). The two biosorbents reached the same maximum sorption capacity (qm = 0.8 mmol/g) for mercury. U. pinnatifida showed a greater affinity (given by the coefficient b of the Langmuir equation) for mercury compared to M. pyrifera (4.4 versus 2.7 L/mmol). Mercury uptake was significantly reduced (by more than 50%) in the presence of competitor heavy metals such as Zn(II), Cd(II) and Ni(II). Samples analysis using an environmental scanning electron microscopy equipped with an energy dispersive X-ray microanalysis showed that mercury was heterogeneously adsorbed on the surface of both biomaterials, while the other heavy metals were homogeneous distributed. The analysis of biosorbents by Fourier transform infrared spectrometry indicated that Hg(II) binding occurred on S=O (sulfonate) and N-H (amine) functional groups. Fil: Plaza Cazón, Josefina del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina. Laboratoire Génie de l‘Environnement Industriel; Francia Fil: Viera, Marisa Rosana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Guibal, Eric. Laboratoire Génie de l‘Environnement Industriel; Francia

Aims: The objective of this study was to apply the knowledge-based approach to the selection of an inoculum to be used in bioaugmentation processes to facilitate phenanthrene degradation in phenanthrene- and Cr(VI)-co-contaminated soils. Methods and Results: The bacterial community composition of phenanthrene and phenanthrene- and Cr(VI)-co-contaminated microcosms, determined by denaturing gradient gel electrophoresis analysis, showed that members of the Sphingomonadaceae family were the predominant micro-organisms. However, the Cr(VI) contamination produced a selective change of predominant Sphingomonas species, and in co-contaminated soil microcosms, a population closely related to Sphingomonas paucimobilis was naturally selected. The bioaugmentation process was carried out using the phenanthrene-degrading strain S. paucimobilis 20006FA, isolated and characterized in our laboratory. Although the strain showed a low Cr(VI) resistance (0·250 mmol l−1); in liquid culture, it was capable of reducing chromate and degrading phenanthrene simultaneously. Conclusion: The inoculation of this strain managed to moderate the effect of the presence of Cr(VI), increasing the biological activity and phenanthrene degradation rate in co-contaminated microcosm. Significance and Impact of the Study: In this study, we have applied a novel approach to the selection of the adequate inoculum to enhance the phenanthrene degradation in phenanthrene- and Cr(VI)-co-contaminated soils.

This work presents an overview of the physicochemical and biological studies focusing on acidophilic microorganisms carried out along Rio Agrio and in different hot springs belonging to the geothermal Copahue–Caviahue system (Neuquen Argentina). This extreme environment is characterized by wide ranges of temperature and pH ( Leptospirillum ferrooxidans , Acidithiobacillus ferrooxidans , Acidithiobacillus thiooxidans and Acidianus spp., among others, were successfully cultivated. Some physiological properties of the isolates and several biotechnological applications of them were studied and the main results are presented in this paper.

Macrocystis pyrifera was used for the recovery of Zn2+ and Cd2+ from slightly acidic solutions (i.e., pH 4). Sorption isotherms were obtained from mono- and bi-component solutions. For the study of metal desorption, EDTA, HNO3 and Ca(NO3)2 were used as eluents. Metal release (Ca2+, Mg2+, K+ and Na+) was monitored in order to evaluate ion exchange mechanisms. After metal sorption/desorption steps the sorbent was characterized using SEM-EDAX analysis. SEM-EDAX analysis also allowed identifying the presence of elements such as Si, Al, Co, Ag, S, P, and Fe in the cell wall. Zinc desorption was almost complete when using 0.1 M nitric acid solution and the sorbent was not significantly damaged by the acidic treatment. Cadmium was completely removed from loaded sorbent when using EDTA, but at the expense of a partial degradation of the biomass as evidenced by the decrease in the intensity of the C and O peaks (SEM-EDAX).

This work presents an overview of the physicochemical and biological studies carried out along Rio Agrio and in different hot springs belonging to the geothermal Copahue volcano system, in Neuquén Argentina. This is an extreme environment characterized by wide ranges of temperature, pH (

In previous studies it has been showed that bacterially produced sulphuric acid is a good leaching agent for laterite tailings. In this work we evaluated heavy metals leaching from low grade laterite ore for cobalt and nickel extraction using sulphuric acid produced in situ by Acidithiobacillus thiooxidans under different culture conditions. In studies where that material was initially added to the cultures, considerable percentages of metals were leached (100 % Mn, 70 % Co, 7.5 % Ni, less than 5 % of Cr and Fe) after 18 days of incubation at low pulp densities (1 % and 2.5 %) of overburden. The maximum percentages were reached when cultures pH was approximately or below than 1.5. At higher pulp densities material was added to the cultures after different pre-cultivating times; also higher sulphur amounts were assayed; in such way about 100 % Mn, 60 % Co, 9 % Ni and Fe and 2.5 % Cr were leached. Although toxic metals were not completely leached, sequential extractions results indicate that these metals are not readily available. All studies finally suggest that bioleaching is a suitable technology for recovery of valuable metals as Co and remediation of mining residues by extraction of heavy metals.

Bioleaching is the biological conversion of an insoluble metal compound into a water soluble form. In this process metal sulfides are oxidized to metal ions and sulfate by acidophilic microorganisms capable of oxidizing Fe2+ and/or sulfur-compounds. The metal solubilization from sulfide minerals is a chemical process which requires Fe3+ reduction. It is an environmentally friendly technique and an economical method for recovering metals that requires low investment and operation costs. In this work we studied the bioleaching of two kinds of acid-soluble copper sulfides, one easily leached by mesophilic bacteria (covellite), and the other one refractory to their activity (chalcopyrite), in acidic media with or without Fe2+ ions. We studied attached and planktonic populations of autotrophic bacteria, such as Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans in pure or mixed cultures. The influence of a heterotrophic microorganism, Acidiphilium cryptum, was also studied. Attachment was evaluated with fluorescence staining and FISH using four specific probes. L. ferrooxidans showed highest initial attachment in all cases. The presence of Ap. cryptum increased the cell attachment compared with the autotrophic pure cultures. It was possible to correlate experimental data with a mechanism of bacterial-metal sulfide oxidation, the polysulfide pathway for acid- soluble metal sulfides.

This report describes the detection and identification of archaea in several sites located in the area of Copahue volcano, Neuquén province, Argentina by mean of different molecular techniques (PCR, DGGE, DNA sequencing and FISH). In order to study the archaea morphology, cultures were examined using different microscopic techniques (SEM, TEM, EFM and AFM). The corresponding archaea were identified as close relative or members of the genus Acidianus as well as other uncultured archaea clones showing a 93% of similarity to each others.

The aim of this work was to determine the microbial diversity of the acid mine drainage (AMD) material collected at an abandoned pyrite mine in Ouro Preto, Brazil. AMD samples were compared to a nickel sulfide column bioleaching pregnant solution which was used as reference. Fluorescent in situ hybridization analyses (FISH) and Denaturing Gradient Gel Electrophoresis (DGGE) were used. FISH analysis was carried out using specific 16S rRNA probes. The extracted DNA was amplified using universal primers for bacterial 16S rRNA genes and analyzed by DGGE. Acidithiobacillus. ferrooxidans was not detected in AMD samples. However, the presence of Acidithiobacillus thiooxidans was confirmed. In other hand, in the bioleaching tanks samples studied, both bacteria species were detected. The non-identified DNA bands were cloned and sequenced for complete characterization.

Cuban serpentines are known as one of the richest deposits of Ni and Co in the world. These ores are usually treated by pyrometallurgy or by hydrometallurgy. These processes generate huge volumes of mining residues, which still contain high amounts of Ni (0.25%) and Co (0.09%). Since metals are partially oxidized, the chance to use sulphur-oxidizing bacteria (Acidithiobacillus thiooxidans) which are able to generate sulphuric acid to leach the residues from CARON process has been evaluated. Thus, in this work, inorganic and organic acids produced by cultures of A thiooxidans or Aspergillus niger respectively were used to study the extraction of Co and Ni from laterite tailings. The results are compared with those obtained in leaching experiments with direct inoculation of those microorganisms. Using A. niger and sucrose as carbon source, 7% Ni and 16% Co were leached after 3 days although there was a significant metal precipitation later. In one-stage batch experiments using A. thiooxidans and elemental sulphur as energy source higher percentages of metal solubilization (100% Ni and 80% Co) were reached after 15 days. In two-stage batch experiments with sulphuric bio-acid the metal recoveries were much higher (79% Ni and 55% Co) than those obtained with citric bio-acid but lower than those reached in one-stage batch experiments. Since the mineral composition of raw material is a crucial parameter to select the suitable leaching agent for oxide ore, the treatment of residual nickel-ferrous material from the CARON process with bio-sulphuric acid produced by cultures of A. thiooxidans could be an attractive alternative in the development of a sustainable technology for the Cuban mining-metallurgy industry.

Cuban serpentines are known as one of the richest deposits of Ni and Co in the world. These ores are usually treated by pyrometallurgy or by hydrometallurgy. These processes generate huge volumes of mining residues, which still contains high amounts of Ni (0.25 %) and Co (0.09 %). Since metals are partially oxidized, the chances to use sulfur-oxidizing bacteria (Acidithiobacillus thiooxidans) which are able to generate sulfuric acid to leach the residues from Caron process have been evaluated. Thus, in this work, inorganic and organic acids produced in cultures with A. niger or A. thiooxidans respectively were used to study the extraction of Co and Ni from laterite tailings. The results were compared with those obtained in leaching experiments with direct inoculation of those microorganisms. 7 and 16 % of Ni and Co were leached after 3 days using A. niger and sucrose as carbon source. In stage batch one using A. thiooxidans and elemental sulfur as energy source higher percentages of metal solubilization were reached after 15 days. In stage batch two experiments were carried out using inorganic and/or organic bioacids. Metal recoveries in stage batch two using sulfuric bioacid were higher (79 % Ni and 58 % Co) than those obtained with citric bioacid (2.4 % Ni, and 38% Co). However metal recoveries using chemical leaching with citric acid were much higher (80.4 % Ni and 50 % Co using 0.5 M citric acid). Since the mineralogy composition of raw material is a parameter very important to select the leaching agent of oxide ore, the leaching of residue nickel-ferrous of the Caron process with bio-sulfuric acid produced in A. thiooxidans cultures could be an attractive alternative in the development of a sustainable technology in Cuban mining-metallurgy industry.

The Copahue geothermal system is a natural extreme environment located at the northern end of the Cordillera de los Andes in Neuquén province in Argentina. The geochemistry and consequently the biodiversity of the area are dominated by the activity of the Copahue volcano. The main characteristic of Copahue is the extreme acidity of its aquatic environments; ponds and hot springs of moderate and high temperature as well as Río Agrio. In spite of being an apparently hostile location, the prokaryotic biodiversity detected by molecular ecology techniques as well as cultivation shows a rich and diverse environment dominated by acidophilic, sulphur oxidising bacteria or archaea, depending on the conditions of the particular niche studied. In microbial biofilms, found in the borders of the ponds where thermal activity is less intense, the species found are completely different, with a high presence of cyanobacteria and other photosynthetic species. Our results, collected during more than 10 years of work in Copahue, have enabled us to outline geomicrobiological models for the different environments found in the ponds and Río Agrio. Besides, Copahue seems to be the habitat of novel, not yet characterised autochthonous species, especially in the domain Archaea., This work was partially supported by grants PICT 2012-0623 and PICT 2013-0630 (ANPCYT)., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

Copahue is a natural geothermal field (Neuquén province, Argentina) dominated by the Copahue volcano. As a consequence of the sustained volcanic activity, Copahue presents many acidic pools, hot springs and solfataras with different temperature and pH conditions that influence their microbial diversity. The occurrence of microbial biofilms was observed on the surrounding rocks and the borders of the ponds, where water movements and thermal activity are less intense. Microbial biofilms are particular ecological niches within geothermal environments; they present different geochemical conditions from that found in the water of the ponds and hot springs which is reflected in different microbial community structure. The aim of this study is to compare microbial community diversity in the water of ponds and hot springs and in microbial biofilms in the Copahue geothermal field, with particular emphasis on Cyanobacteria and other photosynthetic species that have not been detected before in Copahue. In this study, we report the presence of Cyanobacteria, Chloroflexi and chloroplasts of eukaryotes in the microbial biofilms not detected in the water of the ponds. On the other hand, acidophilic bacteria, the predominant species in the water of moderate temperature ponds, are almost absent in the microbial biofilms in spite of having in some cases similar temperature conditions. Species affiliated with Sulfolobales in the Archaea domain are the predominant microorganism in high temperature ponds and were also detected in the microbial biofilms. Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Gonzalez Toril, Elena. Consejo Superior de Investigaciones Cientificas; España Fil: Aguilera Bazán, Ángeles. Consejo Superior de Investigaciones Cientificas; España Fil: Giaveno, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnol.conicet - Patagonia Norte. Instituto de Investigación y Des. En Ing. de Procesos, Biotecnología y Energias Alternativas. Idepa - Subsede San Antonio Oeste; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

The capacity of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans to reduce different concentrations of hexavalent chromium in shake flask cultures has been investigated. A. ferrooxidans reduces 100% of chromium (VI) at concentrations of 1, 2.5 and 5 ppm, but in the presence of 10 ppm only 42.9% of chromium (VI) was reduced after 11 days of incubation. A. thiooxidans showed a lower capacity to reduce this ion and total reduction of chromium (VI) was only obtained for concentrations of 1 and 2.5 ppm, whereas 64.7% and 30.5% was reached for 5 and 10 ppm, respectively, after 11 days. A continuous flow mode system was subsequently investigated, in which A. thiooxidans was immobilized on elemental sulphur and the acidic medium obtained was employed to solubilize chromium (III) and to reduce chromium (VI) present in a real electroplating waste [30% of chromium (III) and 0.1% of chromium (VI)]. The system enabled the reduction of 92.7% of hexavalent chromium and represents a promising way to treat this type of waste in the industry.

In this paper, we report the chromium(VI) reduction by filtrates of Acidithiobacillus and Thiobacillus cultures. Chromium(VI) reduction by filtrates of A. ferrooxidans cultures under acidic conditions was higher than that observed for A. thiooxidans. However, at pH close to 7, chromium(VI) reduction by filtrates of T. thioparus cultures was as high as that by filtrates of A. thiooxidans cultures and much higher than that observed for A. ferrooxidans cultures at the same pH. The capability of these cultures to reduce chromium(VI) was associated specifically with the fraction of cultures (cells, sulphur and associated sulphur compounds) retained by filtration through a 0.45 μm filter. In the fraction that comes from A. thiooxidans culture, polythionates (S x O 6 2− ) with 3–7 sulphur atoms were detected and identified (by HPLC with MS as detector). The model of vesicles containing polythionates, sulphur and water agrees with our results.

Three acidophilic, chemolithotrophic and ferrous oxidizing bacteria were isolated from the Agrio River in the geothermal system of Copahue volcano in Neuquen (Patagonia, Argentina) using 9K enrichment medium and then purified on solid ferrous-agarose medium. Amplified ribosomal DNA restriction enzyme analysis (PCR/ARDRA) showed that these strains can be considered as Acidithiobacillus ferrooxidans. Ferrous iron oxidation of these strains, including a collection strain was compared at different temperatures (20, 25, 30, 35 and 40 °C) and pH values (1.6, 1.8 and 2.3). Isolated bacteria proved to be less susceptible to low temperatures or high medium acidity. These strains showed adequate growth in iron-free 9K medium using sulphur as a sole energy source. Iron(II) oxidation inhibition in the presence of different heavy metals (Ag+, Cd2+, Cu2+, Zn2+) or different anions (NO3−, Cl−) were also investigated.

A simple metabolic model of ferrous oxidizing bacteria based on biochemically structured balances of ATP and NAD(P)H is proposed in order to calculate maximum yield and maintenance on ATP. Similar values of growth yield and maintenance were obtained using data of ferrous iron and/or oxygen consumption in Acidithiobacillus ferrooxidans cultures on iron under different conditions. When pyrite was the sole energy source, growth yield was higher suggesting cells could obtain energy through the sulfur compounds oxidation. Values of growth yields for Leptospirillum ferrooxidans cultures on iron were a bit lower than those obtained for A. ferrooxidans although within the experimental errors. The maintenance coefficients on ATP for both bacteria were similar and comparable to those observed in heterotrophic microorganisms. This fact is really surprising taking in account the high proton gradient that this kind of microorganisms should maintain.

The aim of this investigation was to determine the efficacy of covellite bioleaching using pure cultures of Acidithiobacillus ferrooxidans or Acidithiobacillus thiooxidans and a mixed culture composed of At. thiooxidans and Leptospirillum ferrooxidans. The experiments were carried out in shake flasks with or without iron(II) (1 g/L as ferrous sulphate) at pH 2.0. Inocula of both iron-oxidising bacteria were obtained from cultures with iron(II) as the sole energy source, whereas At. thiooxidans inoculum was taken from a culture growing on sulphur. The solubilisation of copper in flasks inoculated with At. thiooxidans was greatly enhanced in the presence of additional iron(II) achieving 62% copper extraction in 30 days. This result agrees with a mechanism proposed recently. On the other hand, the effect of supplemental iron was not so important for covellite leaching by the At. ferrooxidans culture and the mixed culture. Copper solubilisation by the At. ferrooxidans culture was nearly the same as that for the mixed culture (51% versus 55%).

In this paper, we present the indirect Cr(VI) reduction by Acidithiobacillus thiooxidans using sulfur as energy source under aerobic conditions and the subsequent Cr(III) precipitation by Desulfovibrio sp. under anaerobic conditions. Cr(VI) reduction is promoted by intermediate-products such as sulfite and thiosulfate. Both processes have been operated sequentially under continuous flow conditions to decontaminate a 5 mg l-1 Cr(VI) solution. Fil: Viera, Marisa Rosana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Curutchet, Gustavo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

Thermophiles and hyperthermophiles are present in various regions of the Earth, including volcanic environments, hot springs, mud pots, fumaroles, geysers, coastal thermal springs, and even deep-sea hydrothermal vents. They are also found in man-made environments, such as heated compost facilities, reactors, and spray dryers. Thermophiles, hyperthermophiles, and their bioproducts facilitate various industrial, agricultural, and medicinal applications and offer potential solutions to environmental damages and the demand for biofuels. Intensified efforts to sequence the entire genome of hyperthermophiles and thermophiles are increasing rapidly, as evidenced by the fact that over 120 complete genome sequences of the hyperthermophiles Aquificae, Thermotogae, Crenarchaeota, and Euryarchaeota are now available. In this review, we summarise the major current applications of thermophiles and thermozymes. In addition, emphasis is placed on recent progress in understanding the biodiversity, genomes, transcriptomes, metagenomes, and single-cell sequencing of thermophiles in the genomic era. Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Chan, Kok Gan. University of Malaya; Malasia Fil: Shahar, Saleha. Universiti Teknologi Malaysia; Malasia Fil: Sin, Lee Li. Universiti Teknologi Malaysia; Malasia Fil: Goh, Kian Mau. Universiti Teknologi Malaysia; Malasia

Copahue is an acidic geothermal volcanic region in the northwest corner of Neuquén Province, Argentina. In the area, there are various ponds, pools and hot springs with different temperatures, pH values and levels of anthropogenic influence. In this study, the prokaryotic biodiversity of five representative ponds was studied by using two complementary molecular ecology techniques: phylogenetic analysis of 16S rRNA bacterial and archaeal genes and FISH (or CARD-FISH) for quantitative estimation of biodiversity. The results, supported by multivariate statistical analysis, showed that the biodiversity in Copahue ponds seemed to be determined by temperature. High temperature ponds were dominated by archaea, mainly apparently novel representatives from the orders Sulfolobales and Thermoplasmatales that had no close cultivated relatives. By contrast, moderate temperature ponds were colonised by well-characterised sulphur-oxidising bacteria related to acidic environments, such as other geothermal sites or acid mine drainage, and archaea were absent. By combining the biodiversity results from this study and the reported physicochemical features of Copahue, a preliminary model of the possible biogeochemical interaction was outlined for moderate and high temperature ponds. Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina Fil: Gonzalez Toril, Elena. Consejo Superior de Investigaciones Cientificas; España Fil: Giaveno Filippa, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Comahue; Argentina Fil: Aguilera Bazán, A. Consejo Superior de Investigaciones Cientificas; España Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales. Universidad Nacional de la Plata. Facultad de Cs.exactas. Centro de Investigación y Desarrollo En Fermentaciones Industriales; Argentina

Acidianus copahuensis is a recently characterized thermoacidophilic archaeon isolated from the Copahue volcanic area in Argentina. Here, we present its draft genome sequence, in which we found genes involved in key metabolic pathways for developing under Copahue's extreme environmental conditions, such as sulfur and iron oxidation, carbon fixation, and metal tolerance., Centro de Investigación y Desarrollo en Fermentaciones Industriales

To allow the final disposal of galvanic sludge from a wastewater treatment plant of automotive factory, integrated microbial processes were performed to release and recover nickel and zinc contained in the solid residue. The metals were successfully leached using sulfuric acid continuously produced by Acidithiobacillus thiooxidans biofilm on elemental sulfur. The best condition using a sludge pulp density of 1 % w/v and a dilution rate of 0.22 h−1 100 % allowed more than 90 % of nickel and zinc dissolution, respectively; higher values of dilution rate and/or pulp density decreased the percentages of metal dissolution. The recovery of metals from the leachates was performed by continuous adsorption on Undaria pinnatifida biomass after raising the pH up to 4. Adsorption processes allowed great recoveries of nickel and zinc from monometallic solutions at the lowest flow rate (100 and 90 %); the recoveries from the leachates were not so good and to increase them three fixed bed columns in series were used reaching approximately 50 and 80 % of nickel and zinc recovery respectively, even at high dilution rates (more than 1.5 h−1). This integrated process could be applied on a higher scale.

The ability of Thiobacillus ferrooxidans cultures to reduce chromium(VI) to chromium(III) was evaluated under different conditions. In T. ferrooxidans cultures with sulphur as energy source, the capacity for chromium(VI) reduction was related to the generation of sulphur compounds (sulphite, thiosulphate and polythionates) with high reducing power. In contrast with other chromium(VI)-reducing microorganisms, T. ferrooxidans showed higher chromium(VI) reduction at low pH. The reduction of chromium(VI) also increased with the age of the culture. A T. ferrooxidans cells were capable of growing under anaerobic conditions with chromium(VI) as the terminal-electron acceptor. Fil: QuiIntana, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Curutchet, Gustavo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

Mechanisms involved in bioleaching of an aluminosilicate (95% of spodumene) by heterotrophic microorganisms were investigated. Two moulds (Aspergillus niger and Penicillium purpurogenum) and a yeast (Rhodotorula rubra), all isolated from the mineral, were assayed. The mineral was put into the bioleaching medium under two different conditions: free or into a dialysis tube. The bioleaching mechanism for A. niger or P. purpurogenum was related to the production of low molecular weight metabolites, mainly organic acids. In contrast, bioleaching by R. rubra was related to its metabolic activity and to structural macromolecules of the capsule and the cell wall.

Exocellular polysaccharides were extracted from Thiobacillus ferrooxidans cells grown in the presence of iron. Cells without these compounds could not adhere to covellite. The loss of the layer of exocellular polysaccharides also affected the direct mechanism of bioleaching of covellite in a negative way. This ability to attach to and leach covellite was restored within a few hours when exopolymeric material was produced again. The addition of exocellular compounds to cells stripped of exocellular polymers also restored their ability to the same level as that of untreated cells. Thiobacillus thiooxidans was not able to attach to and leach covellite even when exocellular compounds from Thiobacillus ferrooxidans were added.

A clear relationship was observed between the adhesion of Thiobacillus ferrooxidans and Thiobacillus thiooxidans to different substrates and the nutrient composition of the culture medium used for growth. However, a linear relationship between the percentage of attachment and the efficiency of bioleaching by these microorganisms was not found. The direct attack mechanism on insoluble sulphides by Thiobacillus ferrooxidans was confirmed in the absence of iron.

Copahue is a geothermal field located in the Northwest corner of Neuquén province in Argentina. It is dominated by the still active Copahue volcano. In the area there are many acidic pools, hot springs and solfataras with different temperature and pH conditions that influence their microbial diversity. On the surrounding rocks and the borders of the pools, where water movements and thermal activity are less intense, many biofilms can be found. They have different aspects and structure, and they present less extreme temperature and pH conditions than the ponds and hot springs. Biofilms are a different ecological niche and they have different microbial community structure. In this study carried out by molecular ecology techniques, mainly 16S and 18S rRNA sequencing, we report a strong presence of cyanobacterias, cloroflexi and eukaryotes, not detected in previous biodiversity studies done on water samples. Almost no acidophilic bacteria were found, with the exception of members of genus Thiomonas, also found in the acidic pools. Archaea were detected only in one of the biofilms and the structure of that community seems to be similar to those found in water samples, with many uncultured species mainly related to order Sulfolobales. The aim of this study is to assess microbial community diversity in the biofilms present in this acidic geothermal area, with particular emphasis on detection of cyanobacterias and eukaryotes with potential biotechnological applications like production of alternative energy sources, synthesis and accumulation of biomolecules with antiviral or antibiotic activities or potential ability to bioremediate contaminated areas. Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: González Toril, Elena. Instituto Nacional de Técnica Aeroespacial. Centro de Astrobiología; España Fil: Aguilera, Ángeles. Instituto Nacional de Técnica Aeroespacial. Centro de Astrobiología; España Fil: Giaveno, María Alejandra. Universidad Nacional del Comahue; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

The microbial diversity of sediment in the acidic Agua del Limón hot spring (located in the geothermal Caviahue-Copahue area, Argentina) was investigated using a combination of molecular and cultivation techniques, with particular emphasis on indigenous anaerobic prokaryotes. Bacteria involved in the iron (Acidithiobacillus ferrooxidans and Leptospirillum spp.) and sulfur (Acidithiobacillus spp., Thermotogales-like bacteria, Thiomonas sp., and Desulfurella sp.) cycles were identified in the clone library. Although no obvious sulfate-reducing bacteria were detected by culture-independent techniques, several isolates related to the mesophilic, sporeforming sulfate-reducer "Desulfobacillus acidavidus" strain CL4 were isolated on solid media incubated at both 30°C and 40°C. The 16S rRNA gene of another isolate showed 94% similarity to Desulfotomaculum thermobenzoicum. Enrichment cultur Fil: Willis Poratti, Graciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales (i); Argentina Fil: Hedrich, Sabrina. Bangor University. School of Biological Sciences; Reino Unido Fil: Ñancucheo, Ivan. Bangor University. School of Biological Sciences; Reino Unido Fil: Johnson, D. Barrie. Bangor University. School of Biological Sciences; Reino Unido Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales (i); Argentina

Microbial consortia taken from an extreme environment were grown at different temperatures and enrichment media. The consortia response to environmental changes was evaluated in order to investigate their metabolic flexibility. The molecular technique, DGGE (denaturing gel gradient electrophoresis) was carried out to evaluate the biodiversity. The results show that each consortium was able to grow according to the available resources, demonstrating their flexibility. A selective development was detected when growing conditions were similar to those found in the natural environment even though some species were able to grown even in conditions far away from those present in the sampling sites. Fil: Zurakoski, Natasha. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentina Fil: Giaveno, María A.. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentina Fil: Ulloa, Ricardo J.. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentina Fil: Lavalle, Teresa Laura. Universidad Nacional del Comahue. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentina Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales (i); Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Fermentaciones Industriales (i); Argentina

Background: The increased industrial activity has resulted in the discharge of large amount of pollutants including non-degradable metals into the environment. Chromium is produced in several industrial processes and it can be found in the environment in two stable oxidation states, Cr(VI) and Cr(III). Cr(VI) is more hazardous due to its carcinogenic and mutagenic effects on living organisms. Although much less toxic, Cr(III) can also exert genotoxic effects under prolonged or severe exposure. It can be separated from the solution by precipitation but biosorption using brown algae seems to be an effective and sustainable treatment technique owing to its cost-effectiveness and environmental friendly characteristics. Macrocystis pyrifera and Undaria pinnatifida are two marine brown macroalgae with high capability of removing heavy metals including Cr(III) in batch mode of operation. In this work packed bed biosorption of Cr(III) by M. pyrifera and U. pinnatifida biomasses was evaluated. Results: The shapes of the breakthrough curves were rather different for each biomaterial. Parameters like the breakthrough time (tb) andzone mass transfer (MTZ) showed that U. pinnatifida has greater affinity for Cr(III). The maximum adsorption capacity at the exhaustion operating time (te) demonstrated that M. pyrifera has higher retention capacity of Cr(III). The experimental data were fitted to Thomas, Yoon-Nelson and Dose-Response models. The best correlation coefficient (0.94 or 0.96) was obtained with Dose-Response that accurately describes the uptake behaviour of Cr(III) on the seaweed biomasses under different experimental conditions. The FT-IR spectra evidenced that Cr(III) adsorption occurred mainly by interaction between metal and carboxylate groups present on both the seaweed surfaces. Conclusions: M. pyrifera and U. pinnatifida biomasses are efficient biosorbents for Cr(III) adsorption under a continuous mode of operation although differences between uptake capacities suggest different mechanisms involved in the biosorption., Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales

In the presence of iron, which is always associated with natural sulphide ores, the percentages of copper dissolution in the bioleaching of covellite were 34 and 45 % when Thiobacillus thiooxidans and Thiobacillus ferrooxidans were used together and when an indirect bioleaching with attached bacteria was performed respectively. In the latter, the percentage of copper dissolution was still higher than the percentages obtained with pure cultures (36 % with a T. thiooxidans culture and 40 % with a T. ferrooxidans culture).