细菌素发酵培养基的优化及动力学初步分析

用响应面方法对Lactococcus lactis生产细菌素乳链菌肽的培养基进行了优化。首先用部分重复因子实验对培养基组份蔗糖，大豆蛋白胨，酵母粉，KH₂PO₄,NaCl,MgSO₄·7H2O对乳链菌肽的影响进行评价，并找出主要影响因子为大豆蛋白胨和磷酸二氢钾，前者为负影响，后者为正效应，其它组份对乳链菌肽产量的影响不显著。第二步用最陡爬坡路径逼近最大响应区域。最后用中心组合设计及响应面分析确定主要影响因子的最佳浓度。菌株在优化培养基中的乳链菌肽产量增加1倍为2150(IU/mL)。动力学分析表明，菌株生长与细菌素的产生为部分耦联型，进入对数中期菌体比生长速率和细菌素比产率在优化培养基中均大于优化前培养基。

Culture Medium Optimization and Primary Kinetics Analysis for Nisin Production

Response surface methodology was used to optimize a medium for nisin production of Lactococcus lactis. In the first optimization step the influence of sucrose,soybean peptone,yeast extract,potassium dihydrogen phosphate,sodium chloride,and magnesium sulfur on nisin production was evaluated using a fractional factorial design.Potassium dihydrogen phosphate influenced nisin production positively while soybean peptone affected nisin production negatively.The other components had no significant effect on nisin production.The path of steepest ascent was used to approach the optimal region of the medium composition.In the third step the optimal concentrations of KH\-2PO\-4 and soybean peptone were determined by a central composite design and response surface analysis.The optimized medium allowed nisin production to be increased from 1074 IU/mL to 2150 IU/mL.The kinetic analysis showed that nisin production fasion at optimized and non\|optimized media was not changed and maintained partially growth\|associated.But the specific growth rates and the specific nisin production rates for the strain at the optimized medium were bigger than the ones at the non\|optimized medium after the cells entered the middle of exponential phase.