产褐藻胶裂解酶菌种的筛选、鉴定及发酵条件优化

Screening and Identification of a Bacterial Strain and Optimization of Medium Composition and Culture Conditions for the Production of Alginate Lyase

以褐藻酸钠为唯一碳源,经多次富集和驯化,从养殖场腐烂海带中筛选到一株高产褐藻胶裂解酶的菌株Alg07。依据菌体形态、生理生化特征和16S rRNA基因序列分析,归属于芽孢杆菌属(Bacillus),命名为Bacillusweihaiensis Alg07。通过单因素试验和正交试验,确定菌株Alg07的最佳发酵产酶培养基成分:褐藻酸钠9 g/L、蛋白胨1 g/L、酵母粉3 g/L、NaCl 5 g/L、MgSO4·7H2O 1 g/L、KCl 5 g/L、CaCl2 4 g/L;最佳发酵产酶条件为:250 m L三角瓶装液量40 m L、培养温度30℃、初始发酵pH 6.5、接种量0.5%、摇床转速180 r/min、培养时间24 h。在优化后的培养条件下,褐藻胶裂解酶活力由35 U/m L提高到563 U/m L。

A highly efficient alginate-degrading microorganism was isolated from rotten seaweed through several cycles of enrichment and domestication in liquid medium containing alginate as the sole carbon source. According to morphological, physiological characteristics and 16S rRNA gene sequence analysis, the strain was identified as Bacillus weihaiensis Alg07. Based on the results of single factor experiments and orthogonal array experiments, the optimal liquid fermentation medium contained 9 g/L of alginate, 1 g/L of peptone, 3 g/L of yeast exact, 5 g/L of NaCl, 1 g/L of MgSO4·7H2O, 5 g/L of KCI and 4 g/L of CaCl2. The strain was cultured at 30 ℃, pH 6.5 and 180 r/min for 24 h in 40 mL of the medium using a 250-mL flask, and the inoculum concentration was 0.5% （V/V）. Under these optimal conditions, the activity of alginate lyase was significantly increased from 35 U/mL to 563 U/mL, indicating a 16-fold increase compared with that before optimization.