反芻動物所採食之芻料含有大量植物纖維，在其瘤胃內進行分解與利用，瘤胃爲一厭氧生態系，其中之纖維分解可藉由細菌、真菌及原蟲進行，而以細菌爲主力。微生物依照植物細胞壁之成分不同而分泌多種不同之纖維相關分解酵素，瘤胃內之溫度、pH值、菌種間之交互作用與受質狀況，均會影響瘤胃微生物對纖維分解之程度。纖維分解酵素與纖維之結合，是進行纖維分解之決定步驟，瘤胃內主要的纖維分解菌Fibrobacter succinogenes、Ruminococcus flavefaciens及R. albus均具有附著纖維之機制，部份細菌更可形成纖維素分解酵素複合體，以增加酵素與纖維接觸之機會。瘤胃中纖維分解菌所分泌之纖維素與半纖維素分解酵素，透過異質性協同作用，可將纖維成分之聚葡萄糖與聚木醣進行完全之水解。未來可進一步利用纖維分解後所得之葡萄糖，發酵生產酒精以提供能源。
The ruminant diet was rich in plant fibers and fibers were fermented in the rumen for further utilization. Rumen is an anaerobic ecosystem with numerous microorganisms including bacteria, protozoa and fungi. Fiber degradation was one of the key roles played by these ruminal microorganisms. Microorganisms produced different enzymes to degrade various components of plant cell wall, and the fiber degradation in the rumen was influenced by temperature, pH, microbe-microbe interaction and substrate supplementation. Cellulolytic enzymes' attachment to plant fiber was a key point to initiate fiber degradation in the rumen. The major cellulolytic rumen bacteria including Fibrobacter succinogenes, Ruminococcus flavefaciens and R. albus which were all equipped with cellulose adhesion character, some bacteria can construct cellulosome to enhance cellulose binding mechanism. The complete degradation of cellulose and xyloglucans in plant cell wall was achieved by heterosynergy of bacterial cellulase and hemicellulase. In the future, glucose produced by cellulolytic enzymes after cellulose degradation may be applied in alcohol production as a new alternative energy source.
