产组成型几丁质酶菌株的筛选及产酶条件优化

Screening and Optimized Fermentation of a Bacillus macerans(Strain CCB-1) Constitutive Producing Chitinase

利用两次平板透明圈筛选,结合液体培养,从土壤中分离出1株产几丁质酶细菌,命名为CCB-1.该菌株产几丁质酶不需要几丁质诱导,而且高浓度的葡萄糖不抑制该菌株产几丁质酶,因此该菌株是组成型产几丁质酶.形态学观察和生理生化测定结果表明CCB-1是浸麻芽孢杆菌(Bacillus macerans).在250 mL摇瓶中研究了氮、葡萄糖浓度、pH值、培养温度、几丁质类型和培养时间对CCB-1生长及产酶的影响.CCB-1菌最适产酶条件为:温度37℃;pH 6-pH 7之间;起始葡萄糖浓度8g/L;0.4%的有机氮(如蛋白胨、牛肉膏、酵母膏);0.3%的胶体几丁质或细粉几丁质.CCB-1在优化培养条件下振荡培养60 h产酶最高,达4.23 U/mL.

A strain, named CCB-1, was isolated by a new method. It could secrete chitinase in medium not concluding chitin, and chitinase producing by the strain didn＇t be inhibited by high concentration glucose. Therefore, the strain should be bacteria of constitutive producing extracellular chitinase. A series of morphological and biochemical characteristics reveal that the strain belongs to Bacillus macerans. The effects of nitrogen, glucose, pH, temperature and time of fermentation on chitinase secretion were investigated in 250 mL Erlenmeyer flasks. The optimum temperature and pH for CCB-1 growth and chintinase formation were 37 ℃ and 6.0--7.0, respectively. The suitable nitrogen was peptone, beef extract and yeast extract. Chitinolytic activity was enhanced by glucose and chitin.