β-甘露聚糖酶产生菌的分离、鉴定及产β-甘露聚糖酶最适条件的研究

Studies of the Isolation and Identification of Strain with β-mannanase and Its Enzymology Properties

以采集的土壤样品为试验材料，经过富集培养及分离纯化，筛选出2株产β-甘露聚糖酶的菌株。采用摇瓶培养分别测定其酶活力，其中1株菌株酶活力较高，酶活力达50．36U／ml。生理生化性质鉴定及16SrDNA序列相似性结果表明该菌为假单孢菌（Pseudomonas sp．）。产酶的最适条件研究发现，1g／100ml玉米粉，2g／100ml魔芋粉，pH6．0，32℃为最优产酶条件，酶活力达185．37U／ml，是优化前的3．68倍。该茵产酶迅速，培养12h后已达产酶高峰。粗酶的性质研究发现，该酶是一种酸性的甘露聚糖酶，作用的最适pH为4．0，最适反应温度为55℃；该酶的稳定性较好，在pH4．0～6．0、温度为40—55℃保持较好的稳定性。

Two strains which produced β-mannanase were isolated from soil by enriching and isolating. A strain with the higher enzyme activity of 50.37 U/ml was obtained after the enzyme activity assay. The strain was identified as Pseudomonas sp. by morphological and physiological characteristics analysis and 16S rDNA BLAST. The optimal conditions for producing β-mannanase by the strain were determined 1 g/100 ml maizena, 2 g/100 ml konjak powder, pH6.0 and the optimal temperature was 32℃ , under which the activity of β-mannanase was up to 185.37 U/ml,3.68 times as before. The strain which rapidly produced β-mannanase showed the highest β-mannanase activity after culturing for 12 h. The study of the enzymatic character of the β-mannanase revealed that it was the acidic β-mannanase, and the optimal condition of the enzyme was pH4.0 and 60% , respectively. The activity of β-mannanase was stable at pH4.0 -6.0 and 40 -55%.