Electricity generation by microorganisms in the sediment-water interface of an extreme acidic microcosm

The attachment of microorganisms to electrodes is of great interest for electricity generation in microbial fuel cells (MFC) or other applications in bioelectrochemical systems (BES). In this work, a microcosm of the acidic ecosystem of Río Tinto was built and graphite electrodes were introduced at different points. This allowed the study of electricity generation in the sediment/water interface and the involvement of acidophilic microorganisms as biocatalysts of the anodic and cathodic reactions in a fuel-cell configuration. Current densities and power outputs of up to 3.5 A/m2 and 0.3 W/m2 , , respectively, were measured at pH 3. Microbial analyses of the electrode surfaces showed that Acidiphilium spp., which uses organic compounds as electron donors, were the predominant biocatalysts of the anodic reactions, whereas the aerobic iron oxidizers Acidithiobacillus ferrooxidans and Leptospirillum spp. were detected mainly on the cathode surface. [Int Microbiol 2011; 14(2):73-81]Peer reviewe

Beyond chloride brines: Variable metabolomic responses in the anaerobic organism Yersinia intermedia MASE-LG-1 to NaCl and MgSO4 at identical water activity

Growth in sodium chloride (NaCl) is known to induce stress in non-halophilic microorganisms leading to effects on the microbial metabolism and cell structure. Microorganisms have evolved a number of adaptations, both structural and metabolic, to counteract osmotic stress. These strategies are well-understood for organisms in NaCl-rich brines such as the accumulation of certain organic solutes (known as either compatible solutes or osmolytes). Less well studied are responses to ionic environments such as sulfate-rich brines which are prevalent on Earth but can also be found on Mars. In this paper, we investigated the global metabolic response of the anaerobic bacterium Yersinia intermedia MASE-LG-1 to osmotic salt stress induced by either magnesium sulfate (MgSO) or NaCl at the same water activity (0.975). Using a non-targeted mass spectrometry approach, the intensity of hundreds of metabolites was measured. The compatible solutes L-asparagine and sucrose were found to be increased in both MgSO and NaCl compared to the control sample, suggesting a similar osmotic response to different ionic environments. We were able to demonstrate that Yersinia intermedia MASE-LG-1 accumulated a range of other compatible solutes. However, we also found the global metabolic responses, especially with regard to amino acid metabolism and carbohydrate metabolism, to be salt-specific, thus, suggesting ion-specific regulation of specific metabolic pathways.European Community’s Seventh Framework Program (FP7/2007-013)Peer Reviewe

Electrodo bacteriano aeróbico para ánodo de una pila de combustible sin mediadores redox ni membrana intercambiadora de protones

Fecha de solicitud: 11-12-2008.- Titular: Consejo Superior de Investigaciones Científicas (CSIC)The invention relates to a biological electrode characterised in that it includes bacterial cells of the genus Acidiphilium sp., absorbed on the surface of a conductive electrode which operates under aerobic conditions. The electrode production method comprises the growth of the bacteria in aerobic solution at an acid pH in the presence of a carbonaceous conductive electrode and a nutrient, preferably glucose. The electrode can be used as an anode in a fuel cell.Peer reviewe

Electrochemical growth of Acidithiobacillus ferrooxidans on a graphite electrode for obtaining a biocathode for direct electrocatalytic reduction of oxygen

An aspect in microbial fuel cell research that is currently of great interest is the development of bacterial cathodes. Bacterial cathodes that catalyze oxygen reduction to water at low pH have the advantage of overcoming the kinetic limitations due to the requirement of 4 protons per molecule reduced. In this work we have studied the performance of a biocathode using as electrocatalyst an acidophile microorganism: Acidithiobacillus ferrooxidans. Growth of the microorganism directly on the electrode took place using an applied voltage of 0V vs. SCE as the only energy source and without adding redox mediators to the solution. Current densities of up to 5Am-2 were measured for O2 reduction in the At. ferrooxidans cathode at pH 2.0 and the electrocatalytic wave was shifted 300mV to higher potential compared to the control graphite electrodes without the bacterium. © 2010 Elsevier B.V.We acknowledge financial support from the Comunidad de Madrid (PICOMICRO project S0505/AMB-0259), the Spanish Ministerio de Ciencia e Innovación (projects CTQ2009-12649, FUNCOAT-Consolider CSD2008-00023, MAT2007-66719-C03-01 and MAT2008-1497/nan) and the Fundación Ramón Areces.Peer Reviewe

Bioelectrocatalizadores para Biopilas de Combustible

Trabajo presentado en el Workshop IMDEA Energía-ICP-CSIC, celebrado en Móstoles el 17 de octubre de 2013.N

Extreme environments as Mars terrestrial analogs: The Rio Tinto case

12 pages, 5 figures, 2 tables.-- ISI Article Identifier: 000244695500010.-- Available online Sep 28, 2006.-- Issue title: "Planet Mars II".The geomicrobiological characterization of the Río Tinto (Iberian Pyritic Belt) has recently proven the importance of the iron cycle, not only in the generation of the extreme conditions of the habitat (low pH, high concentration of heavy metals), but also in the maintenance of a high level of microbial diversity. The presence of vast deposits of sulfates and iron oxides on Mars, the main products of the bioleaching of iron containing sulfides found in Río Tinto, and the physico-chemical properties of iron as a source of energy, protection from radiation and oxidative stress as well as pH control, make Río Tinto an interesting Mars terrestrial analog.This work was supported by Grant BOS2002-02148 from the CICYT and Institutional Grants to the Centro de Astrobiología.Peer reviewe

Physicochemical characterization of Acidiphilium sp. biofilms

The biofilm formation of a strain of the extremophile bacterium Acidiphilium sp., capable of donating electrons directly to electrodes, was studied by different surface characterization techniques. We develop a method that allows the simultaneous study of bacterial biofilms by means of fluorescence microscopy and atomic force microscopy (AFM), in which transparent graphitic flakes deposited on a glass substrate are used as a support for the biofilm. The majority of the cells present on the surface were viable, and the growth of the biofilms over time showed a critical increase of the extracellular polymeric substances (EPS) as well as the formation of nanosized particles inside the biofilm. Also, the presence of Fe in Acidiphilium biofilms was determined by X-ray photoelectron spectroscopy (XPS), whereas surface-enhanced infrared absorption spectroscopy indicated the presence of redox-active proteins. Acidiphilium biofilms are grown on graphitic flakes and are characterized by different physicochemical techniques. Combined fluorescence-AFM microscopy is applied to study the biofilm formation over time and to detect nanosized particles that are, in turn, analyzed by X-ray photoelectron spectroscopy and attenuated total reflection surface-enhanced infrared absorption spectroscopy. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Spanish Ministerio de Ciencia e Innovación (projects CTQ2009-12649, MAT2011-26534, MAT2010-18432); Fundación Ramón Areces (project 20100272)Peer Reviewe