影响解淀粉芽孢杆菌GSBa-1产凝乳酶的因素及发酵条件优化研究

Factors affecting production of a milk-clotting enzyme by Bacillus amyloliquefaciens GSBa-1 and optimization of the fermentation conditions

为了提高解淀粉芽孢杆菌GSBa-1发酵产凝乳酶活力,通过单因素试验并采用Plackett-Burman试验设计对影响该菌株发酵产酶条件的6个因素进行评价,筛选出具有显著影响作用的3个因素即发酵温度、发酵时间和装液量,然后通过响应面法探讨此3个主要因素的最优发酵参数水平,获得最佳的发酵产酶条件。结果表明,解淀粉芽孢杆菌GSBa-1发酵产凝乳酶的最佳工艺条件为:发酵温度36℃,发酵时间75h,装液量40%,初始p H为培养基自然p H(6.85),接种量4%,摇床转速160r/min。此条件下解淀粉芽孢杆菌GSBa-1发酵产酶活力为742.42 Su/m L。解淀粉芽孢杆菌GSBa-1发酵产凝乳酶活力经发酵条件优化后得到显著提高,该菌株的发酵产酶及在干酪生产中的应用具有良好的产业化开发前景。

In order to improve activity of milk-clotting enzyme （MCE） by Bacillus amyloliquefaciens GSBa-1, single factor tests and Plackett-Burman design were used to evaluate 6 factors influencing the fermentation conditions of this strain, and 3 factors such as fermentation temperature, time and inoculation amount were identified as the most significant variables. The optimal fermentation conditions for producing MCE were obtained by response surface methodology as fermentation temperature 36℃, time 75h, added liquid volume of 40%, the initial pH as medium natural pH （6.85）, inoculation amount 4%, shaking speed 160r/min. Under these conditions, strain GSBa- 1 was shown to produce MCE with 742.42 Su/mL. The MCE activity produced by strain GSBa-1 was significantly increasedafter optimization of fermentation conditions, and there is a good potential of application of this MCE producing strain in cheese production.