嗜热厌氧纤维素降解细菌的分离、鉴定及其系统发育分析

利用纤维素降解细菌和纤维素粘附的方法分别从新鲜牛粪、高温堆肥和本实验室保存的纤维素降解富集物中分离得到4株嗜热厌氧纤维素降解细菌。分离菌株为革兰氏染色阴性，直的或稍弯曲杆菌，菌体大小为0.4μm～0.6μm×3μm～15μm，严格厌氧，不还原硫酸盐，形成芽孢。多数芽孢着生于菌体顶端。分离菌株能利用纤维素滤纸、纤维素粉Whatman CFII、微晶纤维素、纤维素粉MN300和未经处理的玉米秆芯、甘蔗渣、水稻秸杆。分离菌株在pH6.2～8.9、温度45℃～65℃范围内利用纤维素，最适pH为7.0～7.5，最适温度为55℃～60℃，发酵纤维素产生乙醇、乙酸、H2和CO2。分离菌株还可利用纤维二糖、葡萄糖、果糖、麦芽糖、山梨醇作为碳源。部分长度的16S rDNA序列分析表明，分离菌株EVAI与Clostridium thermocellum具有99.8%相似性。

Isolation, Identification and Phylogenetic Analysis of A Thermophilic Cellulolytic Anaerobic Bacterium

Four strains of thermophilic cellulolytic anaeobic bacteria were isolated from fresh feces, heat compost, cellulolytic mixed culture with a method based on adherence of cellulolytic bacteria to cellulose. The cells of isolates were straight or slightly curved rods that were 0.4 micron-0.6 micron x 3 microns-15 microns, Gram negative, strictly anaerobic, sulfate reduction negative, spore-forming bacteria. Most of the cells had oval terminal spores, while subterminal spores, middle spores, two or more spores also could be observed and spore formation could occurred in any position. The isolates degraded cellulose filter paper, cellulose powder Whatman CF II, microcrystalline cellulose, cellulose powder MN300 and unpretreated maize stem core, sugarcane residue and rice straw. The pH and temperature ranges for growth on cellulose were 6.2-8.9 and 45 degrees C-65 degrees C respectively with the optima, 7.0-7.5 and 55 degrees C-60 degrees C, respectively. The major fermentation products from cellulose were acetic acid, ethanol, CO2, H2. The isolates could ferment cellobiose, glucose, fructose, maltose, and sorbital. The phylogenetic analysis based on 16S rDNA suggested strain EVA1 was the closest relative of Clostridium thermocellum with 99.8% sequence similarity.