Methanogen

About: Methanogen is a research topic. Over the lifetime, 1146 publications have been published within this topic receiving 48254 citations.

The Biochemistry of archaea (archaebacteria)

Abstract: The archaea - their history and significance, C.R. Woese list of contributors central metabolism of the archaea, M.J. Danson bioenergetics of extreme halophites, V.P. Skulachev biochemistry of methanogenesis, L. Daniels and B. Mukhopadhyay bioenergetics and transport in methanogens and related thermophilic archaea, P. Schonheit signal transduction in halobacteria, D. Oesterhelt and W. Marwan ion transport rhodopsins (bacteriorhodopsin and halorhodopsin) - structure and function, J.K. Lanyi proteins of extreme thermophiles, R. Hensel cell envelopes of archaea - structure and chemistry, O. Kandler and H. Konig membrane lipids of archaea, M. Kates the membrane-bound enzymes of the archaea, L.I. Hochstein chromosome structure, DNA topoisomerases, and DNA polymerases in archaebacteria (archaea), P. Forterre and C. Elie transcription in archaea, W. Zillig et al translation in archaea, R. Amilis et al the structure, function and evolution of archaeal ribosomes, C. Ramirez et al halobacterial genes and genomes, L.C. Schalkwyk structure and function of methanogen genes, J.R. Palmer and J.N. Reeve archaeal hyperthermophile genes, J.Z. Dalgaard and R.A. Garrett epilogue, W.F. Doolittle.

Reducing rumen methane emissions through elimination of rumen protozoa

Abstract: Methanogens living on and within rumen ciliate protozoa may be responsible for up to 37% of the rumen methane emissions. In the absence of protozoa, rumen methane emissions are reduced by an average of 13% but this varies with diet. Decreased methane emissions from the protozoa-free rumen may be a consequence of: (1) reduced ruminal dry matter digestion; (2) a decreased methanogen population; (3) an altered pattern of volatile fatty acid production and hydrogen availability; or (4) increased partial pressure of oxygen in the rumen. The decline in methanogenesis associated with removal of protozoa is greatest on high concentrate diets and this is in keeping with protozoa being relatively more important sources of hydrogen on starch diets, because many starch-fermenting bacteria do not produce H2. Because protozoa also decrease the supply of protein available to the host animal, their elimination offers benefits in both decreasing greenhouse gas emissions and potentially increasing livestock production. Strategies for eliminating protozoa are reviewed. None of the available techniques is considered practical for commercial application and this should be addressed.

Diversity of prokaryotes and methanogenesis in deep subsurface sediments from the Nankai Trough, Ocean Drilling Program Leg 190

Abstract: Diversity of Bacteria and Archaea was studied in deep marine sediments by PCR amplification and sequence analysis of 16S rRNA and methyl co-enzyme M reductase (mcrA) genes. Samples analysed were from Ocean Drilling Program (ODP) Leg 190 deep subsurface sediments at three sites spanning the Nankai Trough in the Pacific Ocean off Shikoku Island, Japan. DNA was amplified, from three depths at site 1173 (4.15, 98.29 and 193.29 mbsf; metres below the sea floor), and phylogenetic analysis of clone libraries showed a wide variety of uncultured Bacteria and Archaea. Sequences of Bacteria were dominated by an uncultured and deeply branching ‘deep sediment group’ (53% of sequences). Archaeal 16S rRNA gene sequences were mainly within the uncultured clades of the Crenarchaeota. There was good agreement between sequences obtained independently by cloning and by denaturing gradient gel electrophoresis. These sequences were similar to others retrieved from marine sediment and other anoxic habitats, and so probably represent important indigenous bacteria. The mcrA gene analysis suggested limited methanogen diversity with only three gene clusters identified within the Methanosarcinales and Methanobacteriales. The cultivated members of the Methanobacteriales and some of the Methanosarcinales can use CO2 and H2 for methanogenesis. These substrates also gave the highest rates in 14C-radiotracer estimates of methanogenic activity, with rates comparable to those from other deep marine sediments. Thus, this research demonstrates the importance of the ‘deep sediment group’ of uncultured Bacteria and links limited diversity of methanogens to the dominance of CO2/H2 based methanogenesis in deep sub-seafloor sediments