猪肠道甲烷菌数量稀少，主要定植于结肠，可利用细菌代谢物产甲烷降低氢分压，维持细菌的正常发酵，但相关研究极少。前期研究表明猪后肠甲烷菌和特定细菌对可溶（SDF）和不可溶纤维（IDF）有特异性响应。鉴于甲烷菌有底物偏好性，其群落变化可改变对发酵终产物的移除能力，最终影响纤维发酵效率和动物生长。故本项目将首先以燕麦β-葡聚糖（SDF）或微晶纤维素（IDF）为唯一碳源底物，通过3种不同代谢类型的甲烷菌、多糖利用菌和氢营养细菌的体外共培养，探明甲烷菌不同类群与细菌的共生模式；其次通过添加抑制剂溴氯甲烷构建体外和在体“去甲烷菌”模型，再引入上述3种甲烷菌，比较分析发酵体系或后肠甲烷菌代谢途径，和细菌代谢产物及相关能量代谢通路，结合动物生长性能和消化率，从菌种/株、菌（类）群、整体三个层面探明甲烷菌与细菌共生策略对上述两种纤维发酵模式和效率的影响机制，为靶向调控特定微生物以高效利用不同纤维源提供参考。

Methanogens, mainly colonized in the colon of pigs, can utilize the metabolites of bacteria to produce methane, and in turn, to decrease the hydrogen partial pressure and maintain the fermentation of microbes in the hindgut. Studies associated with the function of methanogens in the gut of pigs are very limited. Our previous researches showed that methanogens and certain bacterial species particularly responded to soluble (SDF) and/or insoluble (IDF) dietary fibers. Due to the substrates preference of different methanogenic species, the alteration of community of methanogens may change their ability to remove the bacterial metabolites, which finally may probably influence the fermentation efficiency of dietary fibers in the hindgut, as well as the growth of pigs. Therefore in current study, to investigate the symbiotic relationship between different methanogenic species and bacteria during the degradation of dietary fibers, three species of methanogens with different metabolic pathways, polysaccharide utilizing bacteria and hydrogenogenic bacterium will be co-cultured in vitro with oat-derived β-glucan (SDF) or microcrystalline cellulose (MCC, IDF) as the unique carbon substrate, respectively. Then the exclusive inhibitor of methanogens, bromochloromethane, will be used to establish in vitro and in vivo “methanogen-removed” models, and the three methanogens mentioned above will be re-inoculated into the models to compared the metabolic pathways of methanogens, and bacterial metabolites as well as the associated energy metabolism pathways in colonic and hepatic tissues of the animals. Furthermore, combing the growth performance and the nutrients digestibility of the pigs, the underlying mechanism of symbiotic strategy between methanogens and bacteria influencing the fermentation efficiency of the two fibers will be revealed on the species/strain, group and the whole levels. Results will provide new reference for the efficient utilization of different fiber sources by targeting the specific microorganisms in the hindgut of pigs.