植物乳杆菌NMGL2的安全性评价及其产细菌素发酵条件优化

Safety Assessment of Lactiplantibacillus plantarum NMGL2 and Optimization of Fermentation Conditions of Bacteriocin-producing

目前乳酸菌发酵产细菌素的含量较低,因此优化产细菌素的发酵条件是最直接的方式。对分离自内蒙古传统干酪的植物乳杆菌NMGL2的抗生素药敏性、溶血性以及全基因组序列进行分析,结果表明该菌株无明显毒力作用,不携带高毒力因子,抗性基因无转移风险。对植物乳杆菌NMGL2产细菌素的发酵条件进行研究,以金黄色葡萄球菌为指示菌,通过单因素实验以及基于接种率、发酵起始pH值、培养温度3个因素的Box-Behnken法三因素三水平的响应面分析,确定植物乳杆菌NMGL2产细菌素的最佳发酵条件是:发酵起始pH 7.0,接种率1.3%,培养温度37℃。验证试验结果显示在此优化发酵条件下获得对指示菌(金黄色葡萄球菌)的抑菌圈直径为13.8 mm,与模型预测值(13.4 mm)基本吻合,拟合率达到96.64%,证明该模型可靠有效。本研究为植物乳杆菌NMGL2发酵生产细菌素及其应用提供了技术参考。

Due to the low yield of bacteriocin in lactic acid(LAB)bacteria fermentation,optimizing fermentation conditions of bacteriocin-producing by LAB is the most direct way.Antibiotic resistance tests,hemolysis tests and and whole genome sequence analysis showed that Lactiplantibacillus plantarum NMGL2 isolated from Inner Mongolian cheese did not carry high virulence factors and had no significant virulence effects and had no risk of metastasis of resistance genes,demonstrating the safety of L.plantarum NMGL2 in phenotype and genotype.Then,the fermentation conditions of bacteriocin produced production by L.plantarum NMGL2 were optimized,with Staphylococcus aureus as the indicator bacteria and the diameter of the antimicrobial ring as the investigation target.First,a single-factor test including inoculation rate,initial fermentation pH,culture temperature and liquid medium volume on bacteriocin production was performed.Based on the results of single-factor test,three significant factors including inoculation rate,initial fermentation pH and culture temperature were optimized by the response surface of the three-factor three-level design of the Box-Behnken method.The optimal fermentation conditions for bacteriocin production by L.plantarum NMGL2 were determined and the results showed that the optimal fermentation conditions were initial fermentation pH 7.0,inoculation rate of 1.3%,culture temperature of 37℃.The verification test results showed that the inhibition zone diameter of the indicator bacteria(Staphylococcus aureus)was 13.8 mm under the optimized fermentation conditions,which was basically consistent with the predicted value of the model(13.4 mm),and the fitting rate reached 96.64%,indicating that the model was reliable and effective.This study provide a technical foundation for he production of bacteriocin by Lactobacillus plantarum NMGL2and its application.