Optimization of Bacteriocin Production by Batch Fermentation of Lactobacillus plantarum LPCO10

Optimization of bacteriocin production by Lactobacillus plantarum LPCO10 was explored by an integral statistical approach. In a prospective series of experiments, glucose and NaCl concentrations in the culture medium, inoculum size, aeration of the culture, and growth temperature were statistically combined using an experimental 2(3)(5-2) fractional factorial two-level design and tested for their influence on maximal bacteriocin production by L. plantarum LPCO10. After the values for the less-influential variables were fixed, NaCl concentration, inoculum size, and temperature were selected to study their optimal relationship for maximal bacteriocin production. This was achieved by a new experimental 3(2)(3-1) fractional factorial three-level design which was subsequently used to build response surfaces and analyzed for both linear and quadratic effects. Results obtained indicated that the best conditions for bacteriocin production were shown with temperatures ranging from 22 to 27°C, salt concentration from 2.3 to 2.5%, and L. plantarum LPCO10 inoculum size ranging from 10(7.3) to 10(7.4) CFU/ml, fixing the initial glucose concentration at 2%, with no aeration of the culture. Under these optimal conditions, about 3.2 × 10(4) times more bacteriocin per liter of culture medium was obtained than that used to initially purify plantaricin S from L. plantarum LPCO10 to homogeneity. These results indicated the importance of this study in obtaining maximal production of bacteriocins from L. plantarum LPCO10 so that bacteriocins can be used as preservatives in canned foods.

本研究采用整合统计学方法，针对植物乳杆菌（Lactobacillus plantarum）LPCO10产细菌素（bacteriocin）的工艺开展优化探索。在一系列前瞻性实验中，本研究通过2^(5-2)五因素两水平部分因子实验设计，对培养基中葡萄糖与氯化钠浓度、接种量、培养通气条件及生长温度进行统计组合，并考察上述因素对植物乳杆菌LPCO10最大细菌素产量的影响。在确定影响程度较低的变量的最优取值后，本研究选取氯化钠浓度、接种量及生长温度，探究三者与细菌素最大产量间的最优关联关系。为此，本研究采用新型3^(3-1)三因素三水平部分因子实验设计完成上述探究，随后基于该实验数据构建响应面（response surface），并对各因素的线性与二次效应进行统计分析。实验结果表明，植物乳杆菌LPCO10合成细菌素的最优条件为：培养温度22~27℃，氯化钠浓度2.3%~2.5%，接种量为10^7.3~10^7.4 CFU/mL，初始葡萄糖浓度固定为2%，且培养过程全程无通气。在该最优条件下，每升培养基的细菌素产量约为初始时从植物乳杆菌LPCO10中纯化得到同源性植物乳杆菌素S（plantaricin S）时的3.2×10^4倍。上述结果表明，本研究对于实现植物乳杆菌LPCO10高产细菌素具有重要的学术与应用价值，可推动细菌素作为天然防腐剂在罐头食品工业中的应用。