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Structure et activité de la communauté des Archaea méthanogènes du rumen en relation avec la production de méthane par les ruminants

Abstract : Methane (CH4) is a major greenhouse gas. Livestock contributes to one third of CH4 produced by human activity in Europe. Methanogenesis is the result of the activity of a specific group of microorganisms, the methanogenic Archaea. This natural process prevents hydrogen accumulation in the rumen, which may affect the optimal feed degradation, but it represents a loss of 2% to 12% of energy consumed by the animal. Reduction of CH4 emissions from ruminants presents therefore economic and environmental benefits and inevitably involves a change in rumen microbial ecosystem. However microbial mechanisms of CH4 production in the rumen are still poorly understood. The objective of this thesis was to relate the production of CH4 with the structure and/or the activity of the methanogenic rumen community. Different models of manipulation of the rumen microbiota such as defaunation (removal of protozoa) and the use of feed known to affect methanogenesis were used. Interactions between methanogenic Archaea and other microorganisms (bacteria and protozoa) were also studied in the complex rumen ecosystem. In this context, tools of molecular biology, to identify key microbial communities, were optimized. Our work allows to conclude that there is no clear relationship between the number of methanogenic Archaea and methanogenesis rate in the rumen. However, reduction in CH4 emissions could be attributed to changes in the diversity of the methanogenic community and the availability of hydrogen. This thesis has shown that changes in the composition and / or metabolic activity of methanogenic Archaea community were associated to the reductions in CH4 emissions observed in our animal trials. A better understanding of microbial mechanisms involved in the production of methane will consider new ways to reduce emissions in ruminants.
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  • HAL Id : tel-00741981, version 2
  • PRODINRA : 181219

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Milka Popova. Structure et activité de la communauté des Archaea méthanogènes du rumen en relation avec la production de méthane par les ruminants. Sciences agricoles. Université Blaise Pascal - Clermont-Ferrand II, 2011. Français. ⟨NNT : 2011CLF22116⟩. ⟨tel-00741981v2⟩

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