培养基与分割发酵优化促进Nisin生物合成

为了提高乳酸乳球菌（Lactococcus lactis）细胞生长和乳酸链球菌素（Nisin）的合成效率，以正交优化法研究培养基分批发酵和分割发酵方式对Nisin生物合成效率的影响。结果表明，优化发酵培养基配方为：5%蛋白胨，3%蔗糖，2%玉米浆，1%酵母浸粉。在此优化条件下，摇瓶培养（11 h）峰值生物量为4.9×109 CFU/mL，较对照提高43%；10 L发酵罐分批发酵峰值生物量、Nisin效价及Nisin合成速率■q分别为7.75×109 CFU/mL、2 573 IU/mL、151.4 IU/（mL·h），较优化前分别提升38.0%、56.6%、38.2%。分批发酵培养18 h Nisin达到峰值后[■q为147 IU/（mL·h）]，以不同比例分割发酵并继续培养7 h，第二次分割（25%）为Nisin合成最适发酵方式，其Nisin平均合成速率达到294 IU/（mL·h），较分批发酵提高了100%。

Improvement of nisin biosynthesis efficiency by optimizations of medium composition and segmentation fermentation

In order to improve cell growth of Lactococcus lactis and Nisin synthesis efficiency, the effects of medium batch fermentation and segmentation fermentation on Nisin biosynthesis efficiency were studied by orthogonal experiments. The results showed the optimized medium formula was peptone 5%, sucrose 3%, corn steep liquor 2%, yeast extract 1%. Under the optimized conditions, the peak biomass in shake flask culture (11 h) was 4.9×109 CFU/ml, which was 43% higher than the control. The peak biomass, nisin titer and average nisin synthesis rate ■q in the 10 L bioreactor of batch fermentation were 7.75×109 CFU/ml, 2 573 IU/ml and 151.4 IU/(ml·h) at the peak biomass, which increased by 38.0%, 56.6% and 38.2%, respectively. When cells growth in batch Nisin reached the peak value at 18 h with ■q of 147 IU/(mL·h), the fermentation culture was partitioned with different proportions to continue culturing for 7 h. The second segmentation (25%) was the optimal fermentation method for nisin synthesis, and the Nisin average synthesis rate reached 294 IU/(ml·h), which was 100% higher than batch fermentation.