一株低温厌氧纤维素降解细菌的分离、鉴定及其酶学性质的研究

Isolation,Identification and Enzymic Characteristics of Cold-adapted,Cellulytic,Anaerobic Bacterium

从若尔盖草甸淤泥中获得一株低温厌氧纤维素菌CD-2,分离菌株革兰氏染色阴性,直杆状,严格厌氧,菌体大小为0.3μm×2.8～3.1μm,生长温度范围5～40℃(最适温度20℃);pH范围6.5～8.0(最适pH7);NaCl浓度范围0.1%～0.4%(最适NaCl浓度0.2%)。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、羟乙基纤维素、木聚糖等。在菌株CD-2的纤维素酶系中,存在外切-β-1,4-葡聚糖酶(C1酶)、内切-β-1,4-葡聚糖酶(Cx酶)和β-葡萄糖苷酶3种组分,最适温度分别为30、30和25℃。该菌株还存在木聚糖酶,最适温度为30℃。通过16S rDNA序列分析表明,菌株CD-2属于梭菌属Clostridium,与C.papyrosolvens的相似性为99.1%。

A strain of cold-adapted, anaerobic bacteria degrading cellulose efficiently was isolated from pelouse sludge of Zoige wetland of Tibetan plateau. The isolated cells were straight rods that were 0.3 μm ×2. g - 3.1 μm, C^ - , strictly anaerobic. The range of growth temperature was 5 - 40 ℃ （ the optimum was 20 ℃ ） ; the pH ranged between 6.5 - 8.0 （ the optimum was 7.0 ） ; the NaCI ranged between 0. 1% - 0.4 % （ the optimum was 0.2 % ）. The isolates could degrade cellulose filter paper, cellulose powder MN300, mieroerystalline cel- lulose, earhoxymethyl cellulose sodium, hydroxyethyleellulose and xylan. The optimum temperature of C1 , Cx and β-glueosidase was 30,30 and 25 ℃. Xylanase was deteeted and the optimum temperature was 30 ℃. The phylogenetie analysis based on 16S rDNA suggested that strain CD-2 was the closest relative of C. Papyrosolvens with 99 % sequence similarity and was identified as a species Clostridium.