李美霖 郭东会 冯惠萍

摘要 从枯树叶及其覆盖的土壤中筛选分离分解纤维素的菌株并进行16S rRNA鉴定，优化其发酵条件。采用CMC-刚果红染色法初筛分解纤维素的菌株，用显微镜观察其形态结构，用16S rRNA序列分析其系统分类地位。单因素试验确定氮源、碳源、pH值和温度对发酵液中羧甲基纤维素酶（CMC）、滤纸酶（FPA）活力的影响。结果表明，分离到1株高效分解纤维素的菌株SKX-1，鉴定SKX-1为蜡样芽胞杆菌（Bacillus cereus）；最优发酵条件为以蛋白胨为氮源、羧甲基纤维素钠（CMC-Na）为碳源，温度37 ℃，pH值为7，发酵培养后，CMC酶活力达到173.3 U/mL，FPA酶活力达到210.5 U/mL。该试验为菌株Bacillus cereus SKX-1的利用提供了理论基础。

关键词 蜡样芽胞杆菌；菌株SKX-1；16S rRNA；发酵条件；优化；纤维素酶

中图分类号 TQ925 文献标识码 A 文章编号 1007-5739（2018）19-0234-03

Abstract Bacterial strains of decomposing cellulose were screened from dead leaves and their covered soil and identified by 16S rRNA.The fermentation conditions were optimized.CMC-Congo red staining was used to screen decomposing cellulose strains，and its morphological structure was observed by microscope.Its systematic classification status was analyzed by 16S rRNA sequence.The effect of nitrogen，carbon，pH and temperature on the activity of CMC and FPA in fermentation broth were determined by single-factor test.The results showed that a strain of high-efficiency cellulose-decomposing（SKX-1） was isolated and identified as Bacillus cereus.The optimal fermentation condition for SKX-1 was taken peptone as nitrogen source，and CMC-Na as carbon source，the activity of CMC and FPA were 173.3 U/mL and 210.5 U/mL under the fermentation conditions of 37 ℃，pH=7.This experiment could provide a theoretical basis for the application of Bacillus cereus SKX-1.

Key words Bacillus cereus；SKX-1；16S rRNA；fermentation condition；optimization；cellulase

纖维素在地球上分布广泛、蕴藏量丰富，普遍存在于植物中，具有可再生性，是可再生资源[1]。通过纤维素酶水解成葡萄糖等物质，进一步发酵生产酒精、单细胞蛋白、有机酸等人类急需的能源食物和化工原料等，不仅使纤维素得到了再次利用，而且对缓解人类食物紧缺以及化工原料等的枯竭具有重要意义。分解纤维素的菌株产生的酶广泛应用于食品工业、饲料工业、纺织工业、造纸工业以及洗涤剂、医药等众多领域。

近年来，能源和环境问题越来越受到人们的关注和重视，纤维素酶既可用于降解秸秆生产乙醇等新型能源，又可用于辅助秸秆还田，因而也日益受到关注[2-4]。但是，就目前而言，现有的纤维素酶产酶菌株的活力还远远不能满足人们生产生活的需要，而且其生产成本过高，不能广泛应用和大量生产。……