Interplay between fermentative and respiratory energy conservation in ruminal Prevotella sp.

普雷沃菌属是瘤胃微生物组中的优势菌属，在瘤胃中对非纤维素多糖和蛋白质的降解具有重要作用。普雷沃氏菌通过代谢活动维持瘤胃氧化还原电位，平衡瘤胃微生物活动。到目前为止，普雷沃氏菌属（Prevotella spp.主要是因为它们的碳水化合物活性酶和蛋白水解特性而被研究。还原途径包括NAD+的产生和整体氧化还原平衡在过去被忽视。申请人的初步研究鉴定了属于普雷沃氏菌属的Na+ -易位NADH：醌氧化还原酶（NQR）蛋白的存在。在瘤胃样品中。另一项使用纯普雷沃氏菌培养物的分析证实了NQR作为该生物体呼吸链中主要氧化还原酶的存在。这种能力可以与富马酸盐的减少相结合。NQR是离子载体莫能菌素的靶标，莫能菌素主要用于预防牛的酮症和减少甲烷排放。由于普雷沃氏菌之前几乎不被认为受到离子载体处理的影响，因此检测到的NQR的存在强烈表明可能的负面影响。因此，在合作研究项目中，我们的目标是了解Na+ -NQR和延胡索酸还原酶催化的NADH：延胡索酸氧化还原如何有助于布氏毕赤酵母发酵天冬氨酸或葡萄糖期间的能量产生（项目1，J. Steuber）。所获得的知识用于解释纯普雷沃氏菌培养物和瘤胃样品的蛋白质组学和代谢组学数据（项目2，J. Seifert）。我们的长期目标是完全重建这些重要的瘤胃细菌的分解代谢反应，并确定可能抑制其在瘤胃中生长并导致瘤胃微生物组失衡对动物产生负面影响的药物。

Prevotella is a predominant genus in the rumen microbiome, there they are important for non-cellulose polysaccharide and protein degradation. Because of their metabolic activities, Prevotella maintain the redox potential in the rumen and balance the rumen microbial activities. So far, Prevotella spp. were mainly studied because of their carbohydrate active enzymes and the proteolytic properties. Reductive pathways including the generation of NAD+ and the overall redox balance were ignored in the past. A preliminary study of the applicants identified the presence of Na+ -translocating NADH:quinone oxidoreductase (NQR) proteins affiliated to Prevotella spp. in rumen samples. Another analyses using a pure Prevotella bryantii culture verified the presence of NQR as the major oxidoreductase in the respiratory chain of this organism. This capacity can be coupled to the reduction of fumarate. The NQR is the target for the ionophore monensin, which is largely used to prevent ketosis in the cattle and to reduce methane emission. As Prevotella were almost not considered to be influenced by the ionophore treatment before, the presence of the detected NQR strongly indicates a possible negative effect. Thus, in the collaborative research project, we aim to understand how NADH:fumarate oxidoreduction catalysed by the Na+ -NQR and the fumarate reductase contributes to energy generation during fermentation of aspartate or glucose by P. bryantii (project 1, J. Steuber). The obtained knowledge is used to interpret proteomic and metabolomic data with pure Prevotella cultures and rumen samples (project 2, J. Seifert). Our long-term goal is a complete reconstruction of the catabolic reactions of these important ruminal bacteria and to identify possible agents, which inhibit their growth in the rumen and result in an imbalanced rumen microbiome with negative effects to the animal.