低温纤维素降解菌的分离与鉴定

Isolation and identifi cation of cellulose-degrading bacteria under low Isolation and identi cation of cellulose-degrading bacteria under low temperature

对内蒙古部分地区土壤中低温降解纤维素的微生物进行研究,以期获得一些高酶活的低温纤维素酶产生菌.采用纯培养的方法,在10℃下培养获得纯培养物.以细菌16S rDNA通用引物PCR扩增后进行序列同源性比对确定种属.以DNS法测定纤维素酶活性,并对酶活较高的菌株进行产酶条件的优化.结果共分离得到55株可低温降解纤维素的菌株,16S rDNA序列分析表明它们分别属于γ-变形菌纲(γ-Proteobacteria)、硬壁菌门(Firmicutes)、放线菌门(Actinobacteria)、拟杆菌门(Bacteroidetes)以及β-变形菌纲(β-Proteobacteria).该55株菌的纤维素酶活性均在22℃下最高.其中菌株CF11在10℃下的酶活在分离得到的55株细菌中最高.通过优化,菌株CF11产纤维素酶的最佳条件初步确定为pH值为6.5,培养时间为10 d,并且是以酵母提取物作为氮源,其纤维素酶活为58.091 IU.因此菌株CF11是一株极具开发潜力的低温纤维素酶产生菌.

The aim of this study was to obtain high enzyme activity cold-active cellulase-producing bacteria by analyzing cellulose-degrading microorganisms from soil in Inner Mongolia. The pure culture method was used to isolate pure culture at 10℃. The strains were identified by analyzing the similarities of 16S rDNA gene sequences of the isolates. Cellulase activity was determined by DNS method. The enzyme-producing conditions of high enzyme activity cellulase-producing strain was further optimized. As a result, 55 cold-active cellulase-producing strains were isolated. The 16S rDNA gene sequences indicated that the strains belonged to y-Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes and fl-Proteobacteria, respectively. The optimum temperature of cellulase activity of the 55 strains was 22℃. Among these strains, CF11 had the highest cellulase activity at 10 %L The optimum cellulase-producing conditions of strain CFll were cultivation for 10 days with medium primary pH 6.5, and yeast extract as nitrogen source. The cellulase activity of strain CFll could reach 58.091 IU under the optimum conditions. Therefore strain CF11 is a cellulose-degrading bacterium, potential in development of cold-active cellulase.