Benthic microbial methanogenesis is a known source of methane in marine systems. In most sediments, the majority of methanogenesis is located below the sulfatereducing zone, as sulfate reducers outcompete methanogens for the major substrates hydrogen and acetate. The coexistence of methanogenesis and sulfate reduction has been shown before and is possible through the usage of noncompetitive sub...

1. Rates of methanogenesis in freshwater sediments have been shown to increase with inputs of phytoplankton biomass. Although many studies have shown the importance of resource quality for decomposition, little is known of the importance of substrate quality on rates of methanogenesis. 2. Here, we studied the effects of lipid content and taxonomic affiliation of phytoplankton biomass on rates o...

The effects of temperature on rates and pathways of CH4 production and on the abundance and structure of the archaeal community were investigated in acidic peat from a mire in northern Scandinavia (68 degrees N). We monitored the production of CH4 and CO2 over time and measured the turnover of Fe(II), ethanol, and organic acids. All experiments were performed with and without specific inhibitor...

The effects of 2-bromoethanesulfonate, an inhibitor of methanogenesis, on metabolism in sludge from a thermophilic (58 degrees C) anaerobic digestor were studied. It was found from short-term experiments that 1 mumol of 2-bromoethanesulfonate per ml completely inhibited methanogenesis from CH(3)COO, whereas 50 mumol/ml was required for complete inhibition of CO(2) reduction. When 1 mumol of 2-b...

Multienzyme complexes catalyze important metabolic reactions in many organisms, but little is known about the complexes involved in biological methane production (methanogenesis). A crosslinking-mass spectrometry (XL-MS) strategy was employed to identify proteins associated with coenzyme M-coenzyme B heterodisulfide reductase (Hdr), an essential enzyme in all methane-producing archaea (methanog...

The contribution of acetate- and H(2)/CO(2)-dependent methanogenesis to total CH(4) production was determined in excised washed rice roots by radiolabeling, methyl fluoride inhibition, and stable carbon isotope fractionation. Addition of > or = 20 mM phosphate inhibited methanogenesis, which then was exclusively from H(2)/CO(2). Otherwise, acetate contributed about 50 to 60% of the total methan...

We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0–25 cm below sea floor) at six stations (70, 145, 253, 407, 990 and 1024 m) along the Peruvian margin (12 S). This oceanographic region is characterized by high carbon export to the seafloor creating an extensive oxygen minimum zone (OMZ) on the shelf, both factors that could favor surface methanogenesis. ...

The metabolic pathways of methane formation vary with environmental conditions, but whether this can also be linked to changes in the active archaeal community structure remains uncertain. Here, we show that the suppression of aceticlastic methanogenesis by methyl fluoride (CH(3)F) caused surprisingly little differences in community composition of active methanogenic archaea from a rice field s...

Maximizing the flow of metabolic hydrogen ([H]) in the rumen away from CH4 and toward volatile fatty acids (VFA) would increase the efficiency of ruminant production and decrease its environmental impact. The objectives of this meta-analysis were: (i) To quantify shifts in metabolic hydrogen sinks when inhibiting ruminal methanogenesis in vitro; and (ii) To understand the variation in shifts of...