酸橙内生菌Bacillus thuringiensis Bt028产几丁质酶的发酵条件优化

为了提高分离自酸橙果实中的一株内生细菌Bacillus thuringiensis Bt028产几丁质酶的性能。采用单因素实验方法考察了培养基组成和发酵条件对该菌株产几丁质酶的影响，并在此基础上采用响应面方法对该菌株产几丁质酶的摇瓶发酵条件进行了优化。单因素实验结果表明胶体几丁质浓度、培养温度和初始pH对该菌株产几丁质酶影响明显；响应面试验结果表明，当胶体几丁质浓度为0.8%、酵母粉浓度为1%、初始pH为6.9、接种量3%、装液量为100 mL/250 mL、30 ℃培养48 h时，该菌株产几丁质酶性能最佳，发酵液中几丁质酶酶活可达10.48 U/mL。研究结果为该菌株几丁质酶的进一步开发与应用奠定了基础。

Fermentation Conditions of Chitinase Producing by the Endophytic Bacterium Bacillus thuringiensis Bt028 Isolated from Sour Orange

In order to improve the chitinase production performance of an endophytic bacterium Bacillus thuringiensis Bt028 isolated from sour orange fruit, the effects of medium composition and fermentation conditions on chitinase production were investigated by single factor test and the shaking flask fermentation conditions of chitinase production were optimized by response surface methodology. The results of single factor test showed that concentration of colloidal chitin, temperature and initial pH had obvious effects on chitinase production. The results of response surface test showed that the optimum fermentation conditions were as follows: Colloidal chitin concentration was 0.8%, yeast powder concentration was 1%, the initial pH was 6.9, inoculation amount was 3%, liquid volume was 100 mL/250 mL, cultured temperature was 30 ℃ and culture time was 48 h. Under these conditions, the highest enzyme activity of the strain fermentation broth was 10.48 U/mL. The studied results laid a foundation for the further development and application of the chitinase produced by Bacillus thuringiensis Bt028.