大熊猫粪便中纤维素降解菌的筛选及其产酶条件的优化

本试验旨在从大熊猫粪便中筛选出能够降解纤维素的菌株,并对该菌株进行鉴定和产酶条件的优化。利用羧甲基纤维素钠(CMC-Na)为唯一碳源的培养基,结合碘液染色法、滤纸分解试验和纤维素酶活力测定,从大熊猫粪便中筛选得到1株纤维素降解菌DL。结合形态学观察、生理生化特征和16S rDNA基因序列同源性分析,初步鉴定该菌株为Paenibacillus cookii LZ033,它是一种产芽孢且好氧的革兰氏阳性菌。为确定菌株DL的最佳产酶条件,选取培养基初始pH、培养温度、摇床转速以及装液量4个因素,在单因素试验结果的基础上,利用正交试验,确定菌株DL的最佳产酶条件为培养基初始pH为6、培养温度为35℃、摇床转速为125 r/min、250 mL三角瓶装液量为100 mL,在此条件下纤维素酶活力(以滤纸酶活力表示)为102.3 U/mL。

Screening of Celluloytic Bacterium from Giant Panda' s Feces and Optimization of Condition for Cellulase Production

This experiment aimed to screen and identify the cellulose-decomposing bacterium isolated from the feces of giant pandas, and condition for producing cellulase was optimized. The cellulase-producing bacterium named DL was isolated from the feces of giant pandas, used the methods of sodium carboxymethylcellulose ( CMC-Na) as unique carbon source and iodine staining, disintegration of filter paper test and measurement of cellulase activity. Based on the morphological observation, physiological and biochemical characteristics and the result of sequences alignment of 16S rDNA, strain DL was identified as Paenibacillus cookii LZ033. The strain of Paenibacillus cookii LZ033 was found to be a spore-forming, gram-positive aerobic bacterium. Medi-um initial pH, culture temperature, shaker speed and liquid medium volume were chosen to determine the opti-mum condition for cellulase production. On the basis of the single factor experiment, the orthogonal experiment was used to analysis the optimum condition for cellulase production of strain DL, which was shown as follows:medium initial pH 6, culture temperature 35 ℃, rotation speed 125 r/min, broth liquid medium volume 100 mL in 250 mL flask. Under the optimum condition, the activity of cellulose ( expressed in filter paper ac-tivity) was up to 102.3 U/mL.