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The effect of trace elements on the metabolism of methanogenic consortia
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In this article, the influence of trace metals, like cobalt, nickel, tungsten and molybdenum on the conversion of methanol and propionate were studied.Abstract:
Trace metals are essential for the growth and metabolism of anaerobic microorganisms, duo to their roles in key enzymes or cofactors of metabolic pathways. The requirement of trace metals has been recognized. But, proper dosing of these metals in anaerobic treatment system as nutrient still is a great challenge, since dosing of a metal at a high concentration is toxic for growth of microorganisms, and dosing of a specific metal may lead out-compete of one group of microorganisms by the other. In order to obtain knowledge for optimization of metal dosing of anaerobic treatment system, the influence of trace metals, like cobalt, nickel, tungsten and molybdenum on the conversion of methanol and propionate were studied in this research. By using cobalt-sufficient medium, a methanogenic enrichment culture was enriched from a thermophilic lab-scale UASB reactor fed with methanol as carbon and energy source. From which a novel thermophilic obligate methylotrophic methanogenic archaeon , strain L2FAW T , was isolated and characterized as Methanomethylovorans thermophila . The growth of strain L2FAW T on methanol is stimulated by the addition of cobalt; the optimal cobalt concentration is 0.5 to 2 M. therefore, cobalt is important for direct methanol conversion by this methanogen. On the other hand, a syntrophic coculture of methanol degradation was enriched from the same sludge by using cobalt deficient medium, which consisted of a homoacetogen and a hydrogenotrophic methanogen. This coculture degrades methanol partially to acetate and partially to methane, depending on the presence of cobalt. Acetate is the main product when cobalt is presence at high concentration; otherwise methane is formed as dominant products. Therefore, cobalt plays a role in the regulation of the pathway of methanol conversion. The optimal cobalt concentration of the coculture for complete methanogenesis from methanol is about 0.1 M. A thermophilic spore-forming bacteria, strain AMP, was isolated from the coculture , and it is most closely related to Moorella thermoacetica based on 16S rRNA analysis. Despite its high DNA-DNA homology with M. thermoacetica , strain AMP differs from M. thermoacetica on its inability to use glucose, formate and H 2 /CO 2 , and its unique hydrogenogenic growth on CO. Moreover, strain AMP can grow on formate in a coculture with a hydrogenotrophic methanogen. It is described for the first time that a bacterium can grow on the conversion of formate to H 2 and bicarbonate provided that hydrogen is consumed by a methanogen. The effect of cobalt and nickel on the corrinoid and F430 content and on growth of Methanosarcina barkeri on methanol was studied. Cobalt and nickel limitation was achieved and competition between cobalt and nickel uptake was observed. Uptake efficiency of cobalt was high at low cobalt concentration and decreased when the cobalt concentration in the medium was increased. Corrinoid and F430 content correlated positively with the cell content of the corresponding metal, but incorporation in the corrinoid and F430 was significant less at low cell metal contents, ranging from 35% to 80% for corrinoid and 5% to 15% for F430. The trace elements tungsten and molybdenum play an essential role in the growth of anaerobic microorganisms. Depletion of tungsten and/or molybdenum in the media did not affect axenic growth of Syntrophobacter fumaroxidans on propionate+fumarate , indicating under these conditions this organism does not have a high tungsten or molybdenum requirement. However, growth of Methanospirillum hungatei on either formate or hydrogen and carbon dioxide required tungsten, and molybdenum can replace tungsten to some extent. Growth of the Syntrophobacter-Methanospirillum coculture on propionate is significantly affected by the addition of these two metals. Measurement of enzyme levels in cell extracts of syntrophically grown cells indicated that the levels of hydrogenase and formate dehydrogenase activity were correlated with the methane formation rates by the cocultures , which suggests both hydrogen and formate play important role in syntrophic propionate oxidation.read more
Citations
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Journal ArticleDOI
Physiology, Ecology, Phylogeny, and Genomics of Microorganisms Capable of Syntrophic Metabolism
Michael J. McInerney,Christopher G. Struchtemeyer,Jessica R. Sieber,Housna Mouttaki,Alfons J. M. Stams,Bernhard Schink,Lars Rohlin,Robert P. Gunsalus +7 more
TL;DR: The availability of the first complete genome sequences for four model microorganisms capable of syntrophic metabolism provides the genetic framework to begin dissecting the biochemistry of the marginal energy economies and interspecies interactions that are characteristic of the syntrophic lifestyle.
Control of interspecies electron flow during anaerobic digestion: significance of formate transfer versus hydrogen transfer during syntrophic methanogenesis in flocs. [Methanobacterium formicicum; Desulfovibrio vulgaris]
J.H. Thiele,J.G. Zeikus +1 more
TL;DR: In this paper, the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon and more electron flow during syntrophic methanogenesis was described and provided a novel mechanism for energy conservation by syntrophic acetogens.
Journal ArticleDOI
Metal supplementation to UASB bioreactors: from cell-metal interactions to full-scale application.
TL;DR: The currently used methods for trace metal dosing into wastewater treatment reactors are overviewed, ways of optimization are suggested and special attention is given to the influence of metal speciation in the liquid and solid phase on bioavailability.
Journal ArticleDOI
Syntrophic Growth on Formate: a New Microbial Niche in Anoxic Environments
TL;DR: Experimental evidence for growth on formate by syntrophic communities of Moorella sp.
Journal ArticleDOI
Trace element supplementation in the biogas production from wheat stillage--optimization of metal dosing.
TL;DR: A trace element dosing strategy for the anaerobic digestion of wheat stillage was developed and it was possible to reduce the dosing of trace elements, which is positive with reference to economic and environmental aspects.
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