高效降解褐藻胶新菌种的筛选、鉴定及产酶条件优化

Isolation,Identification,and Fermentation Optimization of a High Efficient Novel Alginate-degrading Strain

以褐藻酸钠为唯一碳源,从腐烂的海带中筛选出1株高效降解褐藻胶的菌株,根据其形态学特征、生理生化特性和16S rDNA序列分析鉴定该菌株属于白蚁菌属(Isoptericola),命名为嗜盐白蚁菌WX(Isoptericolahalotolerans WX)。菌株WX的最佳培养基组成为:褐藻酸钠6 g/L、蛋白胨5 g/L、酵母粉2.5 g/L、NaCl 25 g/L、MgSO4 2 mmol/L、CaCl2 0.5 mmol/L、KH2PO4 1 mmol/L、FeSO4 0.2 mmol/L、MnSO4 0.3 mmol/L;摇瓶最佳培养条件为:250 mL三角瓶装瓶量50 mL,pH 8.0,培养温度25℃,摇床转速180 r/min,培养时间44 h。2 mmol/LMg2+和0.2 mmol/L Fe2+对酶活力有明显的促进作用。在优化后的培养条件下,褐藻胶裂解酶活力达到432 U/mL,较优化前提高了13倍。此外,嗜盐白蚁菌WX同时具有淀粉酶和褐藻胶裂解酶活性,具有广泛的应用前景。

A high efficient novel alginate-degrading microorganism was isolated from rotten seaweed using sodium alginate as the sole carbon source. Based on the morphological, physiological characteristics and 16S rDNA sequence, the strain was identified as Isoptericola halotolerans WX. The optimized fermentation medium was composed of sodium alginate 6.0 g/L, tryptone 5.0 g/L, yeast extract 2.5 g/L, NaCl 25.0 g/L, MgSO4 2 mmol/L, CaCl2 0.5 mmol/L, KH2PO4 1 mmol/L, FeSO4 0.2 mmol/L, and MnSO4 0.3 mmol/L. The optimal culture condition was that the strain was cultured in 250 mL shake flasks containing 20 mL medium with shaking speed of 180 r/min and initial pH 8.0 at 25 ℃ for 44 h. Besides, 2 mmol/L Mg2＋ and 0.2 mmol/L Fe2＋ had remarkable effect on enzyme activity. Under the optimized conditions, the activity of alginate lyase was increased significantly from 32 U/mL to 432 U/mL, around 13-fold compared with the state without optimization. Additionally, Isoptericola halotolerans WX was demonstrated to possess the activity of amylase, which confers its extensive potential applications.