Abstract: In order to screen and cultivate efficient cellulose degrading strains and improve the efficiency of cellulose degradation，in this study,we screened the strains with strong cellulose degradation ability from rumen fluid,fresh excreta of beef cattle,and locust hindgut,performed biological identification,and compared their enzyme-producing activity. The results showed that the cellulose-degrading bacteria strains L7,L8-1,and L9 were screened from the rumen fluid of Simmental cattle and identified as Bacillus altitudinis,B. siamensis and B. subtillus,respectively. The strains H2-1 and H3-1 were screened from locust hindgut and identified as B. subtillus and B. proteolyticus,respectively,and the strain F8-2 from cattle excreta was identified as B. altitudinis. The strain L7 showed the strongest degradation ability,enzyme activity of which in FPA,CMC,C₁,and β-Gase was 4.28,1.89,5.57,and 2.30 U·mL^-1,respectively. Correlation analysis showed that the D/d values of colony were significantly positively correlated with enzyme activity of FPA,CMC,C₁,and β-Gase (P＜0.05). In this study,the strain L7 showed stronger cellulose degradation ability than other strains,and provided more possibilities to improve the feed conversion rate of crude fiber utilization.

Key words: Cellulose-degrading bacteria, Enzymatic activity, Bacillus

摘要： 为了选育纤维素高效降解菌，提高纤维素降解效率。本研究从肉牛瘤胃液、肉牛粪便，蝗虫肠道末筛选纤维素降解能力较强的株系，对其进行生物学鉴定和酶活性比较。结果表明，从肉牛瘤胃液中筛选出纤维素降解株系L7，L8-1和L9，分别鉴定为高地芽孢杆菌(Bacillus altitudinis)、暹罗芽孢杆菌(B.siamensis)和枯草芽孢杆菌(B.subtillus)；从蝗虫肠道末中筛选得到株系H2-1和H3-1，分别鉴定为枯草芽孢杆菌(B.subtillus)和解蛋白芽孢杆菌(B.proteolyticus)；从肉牛粪便中筛选得到株系F8-2被鉴定为高地芽孢杆菌(B.altitudinis)。其中降解能力最强的株系为L7，其全酶(FPA)、外切葡聚糖酶(C₁)，内切葡聚糖酶(CMC)和β-葡萄糖苷酶(β-Gase)活性分别为4.28，1.89，5.57，2.30 U·mL^-1。菌落D/d平均值与FPA，CMC，C₁，β-Gase的酶活性呈显著正相关(P＜0.05)。本研究筛选得到株系L7具有较强的纤维素降解能力，为提高饲料转化率提供了更多可能。

关键词: 纤维素降解菌, 酶活性, 芽孢杆菌