中温厌氧纤维素菌的分离鉴定,系统发育学分析及其酶学性质的研究

Isolation,Identification,Phylogenetic Analysis and Enzymic Characteristic of Mesophilic Cellulolytic Anaerobic Bacteria

利用厌氧分离技术从泥炭中分离到一株纤维素降解能力较强的中温厌氧细菌。分离菌株为革兰氏染色阳性,直杆或稍弯曲杆状,4.2μm^6.8μm×0.8μm^1.0μm,严格厌氧,不形成芽孢,能运动。分离菌株可在20℃~40℃,pH 6.0~8.5之间利用纤维素生长,最适生长温度为35℃,最适pH 6.8~7.0。分离菌株能利用滤纸、纤维素粉MN300、微晶纤维素、羧甲基纤维素等,还可以利用葡萄糖、纤维二糖、木糖、木聚糖、棉子糖、麦芽糖、山梨糖、胰蛋白胨和水杨苷作为底物。在P4-3的纤维素酶复合体中,滤纸酶,Cx酶和β-葡萄糖苷酶的最适作用温度分别为55℃,55℃和45℃,接种120 h后培养物的胞外纤维素酶液中三种酶的酶活分别为86.25 U.mg-1,20.04 U.mg-1,18.39 U.mg-1。部分长度的16S rDNA序列分析表明,分离菌株P4-3与C lostridium cellulolyticum的序列相似性为99%。

A strain of mesophilic anaerobic bacteria degrading cellulose efficiently was isolated from peat by Hungate technology. The isolated ceils were straight or slightly curved rods that were 4.2μm- 6.8μm × 0.8μm- 1.0μm, Gram positive, strictly anaerobic, motile, without spore-forming. The isolates could degrade cellulose filter paper, cellulose powder MN300, microcrystalline cellulose and carboxymethyl cellulose sodium. The range of growth temperature and pH on cellulose were 20 ℃- 40℃ and 6.0 - 8.5 respectively with the optima of 35 ℃ and 6.8 - 7.0, respectively. The isolates could also utilize cellobiose, glucose, xylose, xylane, raffinose, maltose, sorbose, tryptone and salicin as substrates. The optimum temperatures of FPA, Cx and β-glucosidase was 55℃, 55℃ and 45℃, respectively. The enzymic activities of extracellular FPA, Cx and β-glucosidase collected from 100 hours fermentation broth were 86.25 U · mg^-1, 20.04U ·mg^-1 , 18.39U ·mg^-1, respectively. The phylogenetic analysis based on partial 16S rDNA suggested that strain P4-3 was the closest relative of Clostridium cellulolyticum with 99 % sequence similarity.