纤维素酶产生菌的鉴定及其混合发酵条件优化

Study on Identification of Cellulose-Decomposing Microorganisms and Optimum Conditions for Their Mixed Cultivation

分离筛选到的4株纤维素酶活较高的菌株D6、D7、B7和D1,根据形态特征初步判断为3株细菌、1株放线菌,其16S rDNA序列同源性分析结果发现D6、D7、B7与Bacillus sp.的同源性为99%,系统发育树分析与Bacillus sp.遗传关系最近,D1与Streptomyces zaomyceticus的同源性为99%,系统发育树分析与Streptomyces zaomyceticus遗传关系最近;对4株菌株进行单独与混合发酵培养,结果表明菌株组合D6/D7混合培养后的酶活显著高于其单菌培养,其在培养温度37℃、培养基初始pH值为8.0、接种量为2%(V/V)、D6/D7接种比例为2∶1(V∶V)下的酶活最高,可达到79.42 U/mL。

Four strains of microbes with relatively high cellulase activity named as D6,D7,B7 and D1 were selected;and primarily identified as 3 bacteria and one actinomyces.Based on the results of 16S rDNA sequencing,the homology among strains D6,D7,B7 and Bacillus sp.were 99%;and between D1 and Streptomyces zaomyceticus was also 99%.The phylogenetic tree built on the 16S rDNA sequence indicated that the former three strains had the nearest relationship with Bacillus sp.,while the latter one was nearest to S.zaomyceticus.Enzyme activity of mixed strain D6/D7 was obviously higher than that of single strain.The optimum enzyme-producing conditions were at 37℃,with medium primary pH 8.0,2% of inoculation（V/V）,and inoculation proportion D6∶D7 at 2∶1.Under these conditions,the enzyme activity reached 79.42 U/mL.