To efficiently use lignocellulosic materials in ruminants, it is crucial to explore effective enzymes, especially bifunctional enzymes. In this study, a novel stable bifunctional cellulase-xylanase protein from buffalo rumen metagenome was expressed and characterized, CelXyn2. The enzyme displayed optimal activity at pH 6.0 and 45 °C. The residual endoglucanase and xylanase activities were 90.6% and 86.4% after a 60-min pre-incubation at 55 °C. Hydrolysis of rice straw, wheat straw, sheepgrass and sugar beet pulp by CelXyn2 showed its ability to degrade both cellulose and hemicellulose polymers. Treatment with CelXyn2 improved the hydrolysis of agricultural residues with an evident increase in production of total gas, lactate and volatile fatty acids. The results of 16S rRNA and real-time PCR showed that the effect on in vitro ruminal microbial community depended on fermentation substrates. This study demonstrated that CelXyn2 could strengthen lignocellulose hydrolysis and in vitro ruminal fermentation. These characteristics of CelXyn2 distinguish it as a promising candidate for agricultural application.

为了在反刍动物中有效利用木质纤维素材料，探索有效的酶，尤其是双功能酶至关重要。在这项研究中，表达并表征了一种来自水牛瘤胃宏基因组的新型稳定双功能纤维素酶-木聚糖酶蛋白 CelXyn2。该酶在 pH 6.0 和 45 °C 时表现出最佳活性。在 55 °C 下预孵育 60 分钟后，残留的内切葡聚糖酶和木聚糖酶活性分别为 90.6% 和 86.4%。CelXyn2 对稻草、麦草、绵羊草和甜菜浆的水解表明其能够降解纤维素和半纤维素聚合物。用 CelXyn2 处理改善了农业残留物的水解，明显增加了总气体、乳酸和挥发性脂肪酸的产量。16S rRNA 和实时 PCR 的结果表明，对体外瘤胃微生物群落的影响取决于发酵底物。本研究表明，CelXyn2 可以加强木质纤维素水解和体外瘤胃发酵。CelXyn2 的这些特征使其成为农业应用的有前途的候选者。