Microbial ecosystem and methanogenesis in ruminants.
By D. Morgavi, E. Forano, Cécile Martin, C. Newbold. Animal, 2010
636 citations recorded by the source corpus.
Ruminant production is under increased public scrutiny in terms of the importance of cattle and other ruminants as major producers of the greenhouse gas methane. Methanogenesis is performed by methanogenic archaea, a specialised group of microbes present in several anaerobic environments including the rumen. In the rumen, methanogens utilise predominantly H2 and CO2 as substrates to produce methane, filling an important functional niche in the ecosystem. However, in addition to methanogens, other microbes also have an influence on methane production either because they are involved in hydrogen (H2) metabolism or because they affect the numbers of methanogens or other members of the microbiota. This study explores the relationship between some of these microbes and methanogenesis and highlights some functional groups that could play a role in decreasing methane emissions. Dihydrogen ('H2' from this point on) is the key element that drives methane production in the rumen. Among H2 producers, protozoa have a prominent position, which is strengthened by their close physical association with methanogens, which favours H2 transfer from one to the other. A strong positive interaction was found between protozoal numbers and methane emissions, and because this group is possibly not essential for rumen function, protozoa might be a target for methane mitigation. An important function that is associated with production of H2 is the degradation of fibrous plant material. However, not all members of the rumen fibrolytic community produce H2. Increasing the proportion of non-H2 producing fibrolytic microorganisms might decrease methane production without affecting forage degradability. Alternative pathways that use electron acceptors other than CO2 to oxidise H2 also exist in the rumen. Bacteria with this type of metabolism normally occupy a distinct ecological niche and are not dominant members of the microbiota; however, their numbers can increase if the right potential electron acceptor is present in the diet. Nitrate is an alternative electron sinks that can promote the growth of particular bacteria able to compete with methanogens. Because of the toxicity of the intermediate product, nitrite, the use of nitrate has not been fully explored, but in adapted animals, nitrite does not accumulate and nitrate supplementation may be an alternative under some dietary conditions that deserves to be further studied. In conclusion, methanogens in the rumen co-exist with other microbes, which have contrasting activities. A better understanding of these populations and the pathways that compete with methanogenesis may provide novel targets for emissions abatement in ruminant production.
Subfields: Agronomy and Crop Science, Building and Construction, Soil Science
View Paper: https://www.semanticscholar.org/paper/7dad45e9442cf7834322a25b6d521262de6c4112
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Citations in the corpus
- Special topics--Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options. (2013, neutral): “Morgavi et al. (2010) calculated an average decrease in CH4 production of about 10% due to defaunation, but the data from that study were extremely variable.”
- Interactions between microbial consortia in biofilms: a paradigm shift in rumen microbial ecology and enteric methane mitigation (2014, background): “Theoretically, the generation of CH4 in the rumen can be decreased by the following factors (McAllister and Newbold 2008; Eckard et al. 2010;Morgavi et al. 2010; Cottle et al. 2011;Hristov et al. 2013):”
- The red macroalgae Asparagopsis taxiformis is a potent natural antimethanogenic that reduces methane production during in vitro fermentation with rumen fluid (2016, background): “Enteric CH 4 is a consequence of anaerobic fermentation of feed organic matter (OM) by a microbial consortium that produces substrate CO 2 and hydrogen in a reduction pathway used by methanogens (Morgavi et al .”