高产纤维素酶菌株的筛选、鉴定及产酶特性研究

为了从腐殖质土壤中筛选得到高产纤维素酶菌株,本试验进行了产纤维素酶菌株的筛选、鉴定及其产酶特性研究。首先用羧甲基纤维素钠(CMA-Na)培养基初步分离产纤维素酶菌株,再经过酶活复筛得到一株高产纤维素酶菌株B17。经过形态学和16S rDNA测序鉴定为枯草芽孢杆菌(Bacillus subtilis),并对其发酵产酶条件和酶学性质进行初步研究。试验结果表明,菌株B17的最佳发酵条件为:培养时间3 d、发酵温度35℃、初始pH为6.0,该条件下测得CMC酶活达85.48 U/mL、FPA酶活达59.85 U/mL。酶学性质研究表明:菌株所产纤维素酶最适反应条件为温度50℃、pH为6.0,且具在30～60℃、pH为4.0～7.0范围均具有较高酶活。以上结果表明,本研究所得菌株B17具有较高的开发价值,可应用于农作物秸秆饲料的生产。

Screening and Identification of A Cellulase-producing Bacterium and Analysis of Its Cellulase Characterization

In order to isolate cellulose-producing strain from soil samples of decayed leaf,the screening and identification of a cellulase-producing bacterium and its cellulase characterization were measured in this study.Firstly,the cellulose-producing strain was preliminarily isolated by carboxymethyl cellulose sodium (CMA-Na) culture medium,and then a high-yield cellulase strain B17 was obtained by enzymatic rescreening.Based on morphological observation and 16S rDNA sequencing,B17 was identified as Bacillus subtilis,and then it's fermentation conditions and enzymatic properties were preliminarily explored.The results showed that the optimal fermentation conditions for the cellulose-producting strain B17 were that the cultivate time,temperature and pH were 3 d,35℃ and 6.0.And under this condition,the maximum CMC activity and FPA activity were 85.48 and 59.85 U/mL,respectively.According to the results of enzymatic properties,the optimal temperature and pH for the enzyme were 50℃ and 6.0. Enzyme stability studies showed that enzyme kept active when the temperature was 30 to 60℃ and pH ranged from 4.0 to 7.0.In conclusion,a Bacillus subtilis with high cellulose activity had been isolated and identified,and it had high value for the feed's production of crop straw.