@article {671,
	title = {Metabolism of acetate, methanol, and methylated amines in intertidal sediments of lowes cove, maine.},
	journal = {Appl Environ Microbiol},
	volume = {45},
	year = {1983},
	month = {1983 Jun},
	pages = {1848-53},
	abstract = {The fates and the rates of metabolism of acetate, trimethylamine, methylamine, and methanol were examined to determine the significance of these compounds as in situ methane precursors in surface sediments of an intertidal zone in Maine. Concentrations of these potential methane precursors were generally <3 muM, with the exception of sediments containing fragments of the seaweed Ascophyllum nodosum, in which acetate was 96 muM. [2-C]acetate turnover in all samples was rapid (turnover time <2 h), with CO(2) as the primary product. [C]trimethylamine and methylamine turnover times were slower (>8 h) and were characterized by formation of both CH(4) and CO(2). Ratios of CH(4)/CO(2) from [C]trimethylamine and methylamine in uninhibited sediments indicated that a significant fraction of these substrates were catabolized via a non-methanogenic process. Data from inhibition experiments involving sodium molybdate and 2-bromoethanesulfonic acid supported this interpretation. [C]methanol was oxidized relatively slowly compared with the other substrates and was catabolized mainly to CO(2). Results from experiments with molybdate and 2-bromoethanesulfonic acid suggested that methanol was oxidized primarily through sulfate reduction. In Lowes Cove sediments, trimethylamine accounted for 35.1 to 61.1\% of total methane production.},
	issn = {0099-2240},
	author = {King, G M and Klug, M J and Lovley, D R}
}
@article {672,
	title = {Methanogenesis from methanol and methylamines and acetogenesis from hydrogen and carbon dioxide in the sediments of a eutrophic lake.},
	journal = {Appl Environ Microbiol},
	volume = {45},
	year = {1983},
	month = {1983 Apr},
	pages = {1310-5},
	abstract = {C-tracer techniques were used to examine the metabolism of methanol and methylamines and acetogenesis from hydrogen and carbon dioxide in sediments from the profundal and littoral zones of eutrophic Wintergreen Lake, Michigan. Methanogens were primarily responsible for the metabolism of methanol, monomethylamine, and trimethylamine and maintained the pool size of these substrates below 10 muM in both sediment types. Methanol and methylamines were the precursors for less than 5 and 1\%, respectively, of the total methane produced. Methanol and methylamines continued to be metabolized to methane when the sulfate concentration in the sediment was increased to 20 mM. Less than 2\% of the total acetate production was derived from carbon dioxide reduction. Hydrogen consumption by hydrogen-oxidizing acetogens was 5\% or less of the total hydrogen uptake by acetogens and methanogens. These results, in conjunction with previous studies, emphasize that acetate and hydrogen are the major methane precursors and that methanogens are the predominant hydrogen consumers in the sediments of this eutrophic lake.},
	issn = {0099-2240},
	author = {Lovley, D R and Klug, M J}
}
@article {673,
	title = {Sulfate reducers can outcompete methanogens at freshwater sulfate concentrations.},
	journal = {Appl Environ Microbiol},
	volume = {45},
	year = {1983},
	month = {1983 Jan},
	pages = {187-92},
	abstract = {Acetate and hydrogen metabolism by sulfate reducers and methanogens in the profundal sediments of an oligotrophic lake were examined. Inhibition of sulfate reduction with molybdate stimulated methane production from both hydrogen and acetate. Molybdate did not stimulate methane production in sediments that were preincubated to deplete the sulfate pool. Sulfate reduction accounted for 30 to 81\% of the total of terminal metabolism proceeding through sulfate reduction and methane production in Eckman grab samples of surface sediments. The ability of sulfate reducers to effectively compete with methanogens for acetate was related to the sulfate reducers{\textquoteright} lower half-saturation constant for acetate metabolism at in situ sulfate concentrations. Processes other than sulfate reduction and methanogenesis consumed hydrogen at elevated hydrogen partial pressures and prevented a kinetic analysis of hydrogen uptake by sulfate reducers and methanogens. The demonstration that sulfate reducers can successfully compete with methanogens for hydrogen and acetate in sediments at in situ sulfate concentrations of 60 to 105 muM extends the known range of sediment habitats in which sulfate reduction can be a dominant terminal process.},
	issn = {0099-2240},
	author = {Lovley, D R and Klug, M J}
}
@article {675,
	title = {Intermediary metabolism of organic matter in the sediments of a eutrophic lake.},
	journal = {Appl Environ Microbiol},
	volume = {43},
	year = {1982},
	month = {1982 Mar},
	pages = {552-60},
	abstract = {The rates, products, and controls of the metabolism of fermentation intermediates in the sediments of a eutrophic lake were examined. C-fatty acids were directly injected into sediment subcores for turnover rate measurements. The highest rates of acetate turnover were in surface sediments (0- to 2-cm depth). Methane was the dominant product of acetate metabolism at all depths. Simultaneous measurements of acetate, propionate, and lactate turnover in surface sediments gave turnover rates of 159, 20, and 3 muM/h, respectively. [2-C]propionate and [U-C]lactate were metabolized to [C]acetate, CO(2), and CH(4). [C]formate was completely converted to CO(2) in less than 1 min. Inhibition of methanogenesis with chloroform resulted in an immediate accumulation of volatile fatty acids and hydrogen. Hydrogen inhibited the metabolism of C(3)-C(5) volatile fatty acids. The rates of fatty acid production were estimated from the rates of fatty acid accumulation in the presence of chloroform or hydrogen. The mean molar rates of production were acetate, 82\%; propionate, 13\%; butyrates, 2\%; and valerates, 3\%. A working model for carbon and electron flow is presented which illustrates that fermentation and methanogenesis are the predominate steps in carbon flow and that there is a close interaction between fermentative bacteria, acetogenic hydrogen-producing bacteria, and methanogens.},
	issn = {0099-2240},
	author = {Lovley, D R and Klug, M J}
}
@article {674,
	title = {Kinetic analysis of competition between sulfate reducers and methanogens for hydrogen in sediments.},
	journal = {Appl Environ Microbiol},
	volume = {43},
	year = {1982},
	month = {1982 Jun},
	pages = {1373-9},
	abstract = {The competition between sulfate-reducing and methanogenic bacteria for hydrogen was investigated in eutrophic lake sediments that contained low in situ sulfate concentrations and in sulfate-amended sediments. Sulfate reduction and methane production coexisted in situ in lake surface sediments (0 to 2 cm), but methane production was the dominant terminal process. Addition of 10 to 20 mM sulfate to sediments resulted in a decrease in the hydrogen partial pressure and a concomitant inhibition of methane production over time. Molybdate inhibition of sulfate reduction in sulfate-amended sediments was followed by an increase in the hydrogen partial pressure and the methane production rate to values comparable to those in sediments not amended with sulfate. The sulfate reducer population had a half-saturation constant for hydrogen uptake of 141 pascals versus 597 pascals for the methanogen population. Thus, when sulfate was not limiting, the lower half-saturation constant of sulfate reducers enabled them to inhibit methane production by lowering the hydrogen partial pressure below levels that methanogens could effectively utilize. However, methanogens coexisted with sulfate reducers in the presence of sulfate, and the outcome of competition at any time was a function of the rate of hydrogen production, the relative population sizes, and sulfate availability.},
	issn = {0099-2240},
	author = {Lovley, D R and Dwyer, D F and Klug, M J}
}
