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At least 73 records · Page 4Linked to original sources
PubMed2004

Arsenite oxidation by the heterotroph Hydrogenophaga sp. str. NT-14: the arsenite oxidase and its physiological electron acceptor.

Heterotrophic arsenite oxidation by Hydrogenophaga sp. str. NT-14 is coupled to the reduction of oxygen and appears to yield energy for growth. Purification and partial characterization of the arsenite oxidase revealed that it (1). contains two heterologous subunits, AroA (86 kDa) and AroB (16 kDa), (2). has a native molecular mass of 306 kDa suggesting an alpha(3)beta(3) configuration, and (3). contains molybdenum and iron as cofactors. Although the Hydrogenophaga sp. str. NT-14 arsenite oxidase shares similarities to the arsenite oxidases purified from NT-26 and Alcaligenes faecalis, it differs with respect to activity and overall conformation. A c-551-type cytochrome was purified from Hydrogenophaga sp. str. NT-14 and appears to be the physiological electron acceptor for the arsenite oxidase. The cytochrome can also accept electrons from the purified NT-26 arsenite oxidase. A hypothetical electron transport chain for heterotrophic arsenite oxidation is proposed.

Amino Acid Sequence↗
PubMed2005

Degradation of chlorobenzenes by a strain of Acidovorax avenae isolated from a polluted aquifer.

A subsurface microbial community was isolated from a polluted site of Suquía River (Córdoba-Argentina), acclimated during 15 days in aerobic conditions using 1,2-dichlorobenzene (1,2-DCB) as the sole carbon source. From this acclimated community, we isolated and identified by 16S rDNA analysis a strain of Acidovorax avenae, which was able to perform the complete biodegradation of 1,2-DCB in two days affording stoichiometric amounts of chloride. This pure strain was also tested for biodegradation of chlorobenzene (CB); 1,3-DCB and 1,4-DCB, giving similar results to the experiments using 1,2-DCB. The aromatic-ring-hydroxylating dioxygenase (ARHDO) alpha-subunit gene core, encoding the catalytic site of the large subunit of chlorobenzene dioxygenase, was detected by PCR amplification and confirmed by DNA sequencing. These results suggest that the isolated strain of A. avenae could use a catabolic pathway, via ARHDO system, leading to the formation of chlorocatecols during the first steps of biodegradation, with further chloride release and subsequent paths that showed complete substrate consumption.

Amino Acid Sequence↗
PubMed2005

Inoculation of a submerged filter for biological denitrification of nitrate polluted groundwater: a comparative study.

Activated sludge from a wastewater treatment plant and pure culture of Hydrogenophaga pseudoflava were utilized for the development of a denitrifying biofilm in a submerged filter in order to remove nitrate from polluted groundwater. Nitrate removal efficiency, nitrite accumulation, turbidity, COD and faecal indicators persistence in the treated water were determined at different superficial hydraulic loading (10, 20 and 30 m(3)/m(2) d) and superficial nitrate loading rates (1, 2, 3, 6 and 9 Kg NO(3)(-)/m(2) d) in the submerged filter. The application of H. pseudoflava as inocula allowed better results in terms of system stability, higher superficial hydraulic loading and superficial nitrate loading rates (30 m(3)/m(2)d and 9 kg NO(3)(-) /m(2) d, respectively). These values improve those obtained when the system was inoculated with activated sludge. In addition, the pure microbial inocula improved design parameters and running of the process due to its biofilm homogeneity, obtaining treated water with better characteristics to its final use as drinking water than that obtained with an activated sludge inocula.

Biofilms↗
PubMed2005

A case of sepsis caused by Acidovorax.

This report documents a case of sepsis caused by a recently recognized environmental organism and demonstrates the pathogenicity of this bacterium in the clinical setting.

Blood↗
PubMed2005

A morphological transition in the pleomorphic bacterium Ramlibacter tataouinensis TTB310.

We provide microscopic evidence that motile rod-shaped forms of Ramlibacter tataouinensis TTB310 are formed from dividing cyst-like cells. Careful estimation of the size of the two morphotypes was conducted using optical and transmission electron microscopy (TEM). The cyst-like cell was shown to be a sphere with a diameter Dc=850 nm. The rod-shaped form was a round-ended cylinder with length Lr=2.91 microm and diameter Dr=239 nm. The membrane area of the two morphotypes was the same. However, the formation of rods from cysts involved loss of two-thirds of the cell volume. TEM showed that, prior to division and transition into rods, cysts contained condensed cytoplasmic material. These results suggest that the morphological transition occurs by pure reshaping of cells.

Comamonadaceae↗
PubMed2004

Bioelectric power generation.

In the recent article by Chaudhuri and Lovley, a fuel cell is described in which a microorganism, Rhodoferax ferrireducens, is used to oxidize glucose to carbon dioxide at neutral pH. This reaction occurs via direct bioelectrocatalysis: the microorganism uses the anode itself as the terminal oxidant to which liberated electrons are transferred, and does so with 83% efficiency. These findings are significant because they demonstrate a new approach for harvesting energy from the environment using microorganisms.

Bioelectric Energy Sources↗
PubMed2006

[Construction of sugar-based microbial fuel cells by dissimilatory metal reduction bacteria].

Dissimilatory Metal Reduction Bacteria play an important role in the anaerobic environment. This kind of bacteria gains energy by coupling the oxidation of organic acid or sugars to the reduction of metal oxides. The graphite electrode rode can also be used as the final electron acceptor due to its similarity to solid metal oxides. Based on this biological mechanism, Dissimilatory Metal Reduction Bacteria Rhodoferaxferrireducens was used to construct a suit of microbial fuel cells with sugars as fuel, and the process and mechanism of electricity generation was studied. Rhodoferax ferrireducens was inoculated into the anode chamber in which a graphite electrode served as the final electron acceptor and glucose as the sole electron donor. It was showed that current density was up to 158mA/m2 with the resistance of 510omega at the normal temperature (platform voltage was around 0.46V, the effectual electrode surface was 57cm2). Following 20days' growth a large amount of bacteria cells attached to the electrode surface had been observed through the SEM images. The plandtonic cell protein concentration was 140mg/L and the attached biomass of electrode surface was 1180mg/m2 determined by the Bradford method, which indicated quite a few bacteria attached to the electrode. By analyzing the voltage value measured by the data acquisition system, it was proved that microbial electricity generation attributed mainly to the electrochemically and biologically active cells attached to the electrode, while the planktonic cells had no ability to catalyze electricity generation and almost had not electrochemically and biologically active. Furthermore, this kind of microbial fuel cells exhibited a good electrochemical cycle property and proved to be efficient in biomass utilization and energy restore since other sugars like fructose, sucrose, even xylose, could be oxidized and finally decomposed. Vast waste biomass in the form of carbohydrates is discarded in the environment. Not only is contamination of the environment caused by the discarded biomass, but also abundant energy stored in the biomass is drained away in vain. The sugar-based microbial fuel cells constructed by Rhodoferax ferrireducens could effectively transform the energy stored in sugars into electricity. Meanwhile, the microbial fuel cells presented in this paper, which could work cleanly at normal temperature with a good cycle property, showed a promising future application in this field.

Bioelectric Energy Sources↗
PubMed2003

Bacterial batteries.

Explore the source record for details and available documents.

Bioelectric Energy Sources↗
PubMed2003

Electricity generation by direct oxidation of glucose in mediatorless microbial fuel cells.

Abundant energy, stored primarily in the form of carbohydrates, can be found in waste biomass from agricultural, municipal and industrial sources as well as in dedicated energy crops, such as corn and other grains. Potential strategies for deriving useful forms of energy from carbohydrates include production of ethanol and conversion to hydrogen, but these approaches face technical and economic hurdles. An alternative strategy is direct conversion of sugars to electrical power. Existing transition metal-catalyzed fuel cells cannot be used to generate electric power from carbohydrates. Alternatively, biofuel cells in which whole cells or isolated redox enzymes catalyze the oxidation of the sugar have been developed, but their applicability has been limited by several factors, including (i) the need to add electron-shuttling compounds that mediate electron transfer from the cell to the anode, (ii) incomplete oxidation of the sugars and (iii) lack of long-term stability of the fuel cells. Here we report on a novel microorganism, Rhodoferax ferrireducens, that can oxidize glucose to CO(2) and quantitatively transfer electrons to graphite electrodes without the need for an electron-shuttling mediator. Growth is supported by energy derived from the electron transfer process itself and results in stable, long-term power production.

Bioelectric Energy Sources↗