为获得具有潜在工业应用价值的碱性β-甘露聚糖酶产生菌株,从自然土样中分离得到1株产酶性状较好的碱性细菌,经形态学和分子生物学分析鉴定为科氏芽孢杆菌(Bacillus cohnii)。粗酶性质研究显示,该菌株所产β-甘露聚糖酶最适作用温度和pH分别在55 ℃和9.5。通过单因素和正交设计试验优化后,该菌株摇瓶发酵至36 h时,产酶水平为345 U/L,是优化前产酶水平的4.3倍。研究结果为碱性β-甘露聚糖酶的放大发酵奠定了基础,为碱性β-甘露聚糖酶编码基因的克隆及异源表达等相关研究提供了良好的菌种资源。
In this research, an alkaline β-mannanase-producing strain was obtained and studied for potential industrial application. An alkaline bacterium with good enzyme-producing properties was isolated from natural soil. The strain was further identified as Bacillus cohnii using morphological and molecular biological analysis. After optimization using single-factor method and orthogonal experimental design, the amount of enzyme produced using shaking flask fermentation for 36 h was 345 U/L, which was 4.3 times of that before optimization. The optimum condition of the crude β-mannanase extract was determined to be at 55 ℃ and pH of 9.5. The results laid a foundation for scale-up fermentation of alkaline β-mannanase and provided a good strain for cloning and heterologous expression of alkaline β-mannanase encoding gene.
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