产中性纤维素酶耐碱芽孢杆菌的筛选及酶学性质研究

采用CMC碱性平板筛选方法,从造纸厂碱性淤泥中获得产中性纤维素酶的耐碱枯草芽孢杆菌C3004。根据其形态特征、生理生化特性和16S rRNA序列分析鉴定该菌株为枯草芽孢杆菌,并命名为Bacillus subtilis C3004。液体摇瓶培养24 h产生CMC酶活力达46.6 U/mL。酶学性质初步研究显示,CMC酶反应的pH值以7.0左右为适;在弱酸和碱性条件下也具有较高的酶活和一定的稳定性;反应温度以50℃左右为宜;且具有较好的热稳定性。Mn~(2+)与Fe~(3+)对酶反应有促进作用,Cu~(2+)、Mg~(2+)和Zn~(2+)对酶反应有抑制作用。该菌可在碱性(pH 8.5～10)条件下培养,具有不易被杂菌污染的特点。

Screening of Bacillus strain producing neutral cellulase and characterization of enzymatic reactions

A bacterium strain C3004 producing neutral cellulase was isolated from alkaline silt at the site of paper mill and was identified taxonomically as Bacillus subtilis according to morphological, physiological and biochemical characteristics and 16S rRNA sequence analysis. Under optimum conditions, the neutral cellulase activities （CMCase） of shaking flask culture for 24 h were 46.6 U/mL. The optimal conditions for the enzymatic reaction were about 50℃ and pH 7.0. At pH 6.5-8.7, the enzyme showed high activity and good stability. Mr^2＋ and Fe^3＋ were the activators of the enzyme while Cu^2＋ , Mg^2＋ and Zn^2＋ were the inhibitors. This strain could be cultured in high pH （8.5-10） medium, helping to reduce the risk of contamination by other microorganisms in the course of fermentation on a large scale.