The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform
Ming Hung Wong - One of the best experts on this subject based on the ideXlab platform.
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inhibitory effects of skeletonema costatum on mercury methylation by geobacter sulfurreducens pca
Chemosphere, 2019Co-Authors: Lingyun Ding, Ningning He, Shengchun Wu, Ming Hung Wong, Sai Yang, Peng Liang, Lijuan ZhangAbstract:Abstract Algae and mercury (Hg) are ubiquitous in marine environments. In this study, we investigated the effects of a typical marine algae of diatom Skeletonema costatum on Hg methylation by an Iron-Reducing Bacterium of Geobacter sulfurreducens (G. sulfurreducens) PCA. In the absence of Skeletonema costatum, the bacterial MeHg production rate maximized at 104.06 ± 11.7 ng L−1 h−1 with a high Hg level, while the highest methylation efficiency was achieved at a low Hg concentration. The existence of Skeletonema costatum greatly inhibited the capability of G. sulfurreducens PCA to methylate Hg. With the increase in algal biomass, there was a significant mitigation of MeHg formation and Hg0 release, leaving a considerable proportion of immobilized Hg2+ species (up to 47%) associated with algal cell materials. These results suggest that marine algae are crucial in determining the bioavailability of Hg contaminants and the methylating potential of G. sulfurreducens PCA.
John F Stolz - One of the best experts on this subject based on the ideXlab platform.
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evidence for iron dependent nitrate respiration in the dissimilatory iron reducing Bacterium geobacter metallireducens
Applied and Environmental Microbiology, 2001Co-Authors: John M Senko, John F StolzAbstract:The dissimilatory Iron-Reducing Bacterium Geobacter metallireducens was found to require iron at a concentration in excess of 50 μM for continuous cultivation on nitrate. Growth yield (∼3-fold), cytochrome c content (∼7-fold), and nitrate (∼4.5-fold) and nitrite (∼70-fold) reductase activities were all increased significantly when the growth medium was amended with 500 μM iron.
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a heme c containing enzyme complex that exhibits nitrate and nitrite reductase activity from the dissimilatory iron reducing Bacterium geobacter metallireducens
Archives of Microbiology, 1999Co-Authors: Francisco Martinez Murillo, Theresa Gugliuzza, John M Senko, Partha Basu, John F StolzAbstract:Nitrate reduction in the dissimilatory Iron-Reducing Bacterium Geobacter metallireducens was investigated. Nitrate reductase and nitrite reductase activities in nitrate-grown cells were detected only in the membrane fraction. The apparent K m values for nitrate and nitrite were determined to be 32 and 10 μM, respectively. Growth on nitrate was not inhibited by either tungstate or molybdate at concentrations of 1 mM or less, but was inhibited by both at 10 and 20 mM. Nitrate and nitrite reductase activity in the membrane fraction was not, however, affected by dialysis with 20 mM tungstate. An enzyme complex that exhibited both nitrate and nitrite reductase activity was solubilized from membrane fractions with CHAPS and was partially purified by preparative gel electrophoresis. It was found to be composed of four different polypeptides with molecular masses of 62, 52, 36, and 16 kDa. The 62-kDa polypeptide [a low-midpoint potential (–207 mV), multiheme cytochrome c] exhibited nitrite reductase activity under denaturing conditions. No molybdenum was detected in the complex by plasma-emission mass spectrometry.
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evidence for a novel nitrate reductase in the dissimilatory iron reducing Bacterium geobacter metallireducens
Fems Microbiology Letters, 1993Co-Authors: Rajesh R Naik, Francisco Martinez Murillo, John F StolzAbstract:Nitrate induced the expression of a membrane-bound nitrate reductase in the strict anaerobe Geobacter metallireducens. A fraction from a DEAE cellulose column which showed nitrate reductase activity contained polypeptides of Mr, 18, 36 and 43 K and three c type cytochromes (Mr 28, 46 and 68 K). Western and Southern blot analysis revealed no homology between the nitrate reductase from G. metallireducens and the nitrate reductases from respiratory (Escherichia coli) and denitrifying bacteria (Pseudomonas stutzeri, Pseudomonas aeruginosa) which were shown to be related. These data, in addition to this organism's inability to use fumarate or formate, suggest that its nitrate reductase is novel.
Douglas C. Nelson - One of the best experts on this subject based on the ideXlab platform.
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Mercury Methylation from Unexpected Sources: Molybdate-Inhibited Freshwater Sediments and an Iron-Reducing Bacterium
Applied and Environmental Microbiology, 2006Co-Authors: Emily J. Fleming, E. Erin Mack, Peter G. Green, Douglas C. NelsonAbstract:Methylmercury has been thought to be produced predominantly by sulfate-reducing bacteria in anoxic sediments. Here we show that in circumneutral pH sediments (Clear Lake, CA) application of a specific inhibitor of sulfate-reducing bacteria at appropriate concentrations typically inhibited less than one-half of all anaerobic methylation of added divalent mercury. This suggests that one or more additional groups of microbes are active methylators in these sediments impacted by a nearby abandoned mercury mine. From Clear Lake sediments, we isolated the Iron-Reducing Bacterium Geobacter sp. strain CLFeRB, which can methylate mercury at a rate comparable to Desulfobulbus propionicus strain 1pr3, a sulfate-reducing Bacterium known to be an active methylator. This is the first time that an Iron-Reducing Bacterium has been shown to methylate mercury at environmentally significant rates. We suggest that mercury methylation by Iron-Reducing bacteria represents a previously unidentified and potentially significant source of this environmental toxin in iron-rich freshwater sediments.
Régine Basséguy - One of the best experts on this subject based on the ideXlab platform.
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Assessment of Anticorrosion Properties of Biomineralized Induced Coating formed on Al Alloy in Marine Environment. A new Nature-Inspired Approach for Corrosion Protection.
2020Co-Authors: Maria-joao Figuereido Marques, Teresa C. Diamantino, Régine BasséguyAbstract:Among the strategies employed to protect metallic materials, coatings can be considered as one of the most successful and cost-effective alternatives to efficiently increase the service lifetime of metallic structures, particularly in industries that are continuously exposed to changing and hard weather conditions such as shipbuilding, automobile, aerospace, marine and oil & gas energy infrastructures. However, towards a more constraining legislation as REACH, the surface treatment & coating Industry is at the forefront in developing innovative and even more sustainable products. In the anticorrosion domain, Nature is a fruitful provider of new concepts for green solutions. Biomineralization is a widespread phenomenon that leads to the formation of different biological minerals and has been a large source of inspiration for a variety of fields, ranging from biotechnology, geotechnology, paleobiology to civil engineering and with relevant importance in biomedical research. Comparatively, in the research area of Anticorrosive Coatings, biomineralization has been an underdeveloped approach. Recently, some scientific publications in the field of corrosion and protection have mentioned the advantage of biogenic mineral precipitation on materials surface protection [1, 2]. Notwithstanding these observations, mostly performed in laboratory, the fact that the biomineralization film formed on metal surface can reduce corrosion has been insufficiently explored and should be considered as novel and eco-friendly start-point to produce anticorrosion solutions. Aluminium is currently the second most used metal in the world, providing advantages like low weight, maintenance costs savings, easy workability and recyclability. More specifically, the aluminium-magnesium alloy (Al-Mg) of the 5XXX series is commonly used in marine industry due to corrosion resistance. The main goal of this study is to prove the anticorrosive behaviour of naturally coating formed by biomineralization process on AA5083 alloy surface during estuarine exposure. Experimental work included accelerated salt spray test performed on AA 5083 samples with 2 and 3 years of immersion in Tejo estuary and without exposure. Morphological and chemical characterisation by SEM/EDS, surface and cross-section, were performed before and after the accelerated ageing test. [1] C. Cote, O. Rosas, R. Basseguy, “Geobacter sulfurreducens: An iron reducing Bacterium that can protect carbon steel against corrosion?” Corrosion Science, 94, 2015. [2] Yuanyuan Shen et al, “Study of pitting corrosion inhibition effect on Al alloy in seawater by biomineralized film“, Bioelectrochemistry, 132, 2020.
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Geobacter sulfurreducens: An iron reducing Bacterium that can protect carbon steel against corrosion?
Corrosion Science, 2015Co-Authors: Claudia Cote, Omar Rosas, Régine BasséguyAbstract:The effect of Geobacter sulfurreducens on the electrochemical behaviour of carbon steel in anaerobic phosphate solution is studied here. In natural environments, G. sulfurreducens is able to reduce Fe(III) to Fe(II) during the oxidation of acetate. High availability of Fe(II) promoted the formation of an iron (II) phosphate layer on the steel. It is assumed that this phosphate layer, formed only when bacteria were present, is responsible for maintaining the corrosion potential stable even after intrusion of air. In contrast, the corrosion potential in the abiotic experiments suffered an increase of 450 mV after few hours of exposure to air.
Gill G Geesey - One of the best experts on this subject based on the ideXlab platform.
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role of outer membrane c type cytochromes mtrc and omca in shewanella oneidensis mr 1 cell production accumulation and detachment during respiration on hematite
Geobiology, 2012Co-Authors: Andrew C Mitchell, L Peterson, Catherine L Reardon, Samantha B Reed, David E Culley, Margaret F Romine, Gill G GeeseyAbstract:The Iron-Reducing Bacterium Shewanella oneidensis MR-1 has the capacity to contribute to iron cycling over the long term by respiring on crystalline iron oxides such as hematite when poorly crystalline phases are depleted. The ability of outer membrane cytochromes OmcA and MtrC of MR-1 to bind to and transfer electrons to hematite has led to the suggestion that they function as terminal reductases when this mineral is used as a respiratory substrate. Differences in their redox behavior and hematite-binding properties, however, indicate that they play different roles in the electron transfer reaction. Here, we investigated how these differences in cytochrome behavior with respect to hematite affected biofilm development when the mineral served as terminal electron acceptor (TEA). Upon attachment to hematite, cells of the wild-type (WT) strain as well as those of a ΔomcA mutant but not those of a ΔmtrC mutant replicated and accumulated on the mineral surface. The results indicate that MtrC but not OmcA is required for growth when this mineral serves as TEA. While an OmcA deficiency did not impede cell replication and accumulation on hematite prior to achievement of a maximum surface cell density comparable to that established by WT cells, OmcA was required for efficient electron transfer and cell attachment to hematite once maximum surface cell density was achieved. OmcA may therefore play a role in overcoming barriers to electron transfer and cell attachment to hematite imposed by reductive dissolution of the mineral surface from cell respiration associated with achievement of high surface cell densities.