Zhou X X, Pan Y J, Wang Y B, Li W F
Inst. of Chemical Biology and Pharmaceutical Chemistry, Zhejiang Univ., Hangzhou, China.
J Food Sci. 2008 Aug;73(6):M245-9. doi: 10.1111/j.1750-3841.2008.00836.x.
Nisin is an effective food biopreservative widely used in food industry. However, 1 problem of concern is limited production rate and final nisin concentration. A nisin-producing strain, L. lactis Lac2, a mutant strain with high yield of nisin, was obtained in our laboratory recently. In the present study, a fractional factorial design was applied to investigate the main factors that affect the yield of L. lactis Lac2. Central composite experimental design and response surface methodology were adopted to derive a statistical model for optimizing the composition of the medium. The results showed that the optimum medium for nisin production of L. lactis Lac2 was composed of 2.68% sucrose (w/v), 0.5% tryptone (w/v), 1% yeast extract (w/v), 0.3% Tween-80 (w/v), 0.02% MgSO4.7H2O (w/v), 0.81% NaCl (w/v), 1.91% K2HPO4 (w/v), 0.05% ascorbic acid (w/v), and 2% agar (w/v) (if necessary) at pH 6.5. When cultured in the optimum medium, the nisin yield is an average of 3381.81 IU/mL, which nearly doubled the yield when incubated in the initial medium. Also, the concentration of tryptone was decreased while that of the sucrose was increased when compared with CM broth, which means a reduction of the fermentation cost.
乳酸链球菌素是一种有效的食品生物防腐剂，广泛应用于食品工业。然而，一个令人关注的问题是其生产率和最终乳酸链球菌素浓度有限。最近我们实验室获得了一株产乳酸链球菌素的菌株——乳酸乳球菌Lac2，它是一种高产乳酸链球菌素的突变菌株。在本研究中，采用分数析因设计来研究影响乳酸乳球菌Lac2产量的主要因素。采用中心复合实验设计和响应面方法来推导优化培养基组成的统计模型。结果表明，乳酸乳球菌Lac2产乳酸链球菌素的最佳培养基由以下成分组成：2.68%蔗糖（w/v）、0.5%胰蛋白胨（w/v）、1%酵母提取物（w/v）、0.3%吐温-80（w/v）、0.02%七水硫酸镁（w/v）、0.81%氯化钠（w/v）、1.91%磷酸氢二钾（w/v）、0.05%抗坏血酸（w/v），必要时添加2%琼脂（w/v），pH值为6.5。在最佳培养基中培养时，乳酸链球菌素产量平均为3381.81 IU/mL，几乎是在初始培养基中培养时产量的两倍。此外，与CM肉汤相比，胰蛋白胨浓度降低而蔗糖浓度增加，这意味着发酵成本降低。
