植物乳杆菌对食源性病原菌作用的研究

通过牛津杯法筛选得到几株高抑菌活性的植物乳杆菌，使用蛋白酶K和NaOH对这几株杆菌的发酵液上清进行处理，以大肠杆菌O157:H7和金黄色葡萄球菌为指示菌，发现有机酸为主要抑菌物质，但是调节pH值至6.5后的发酵上清液可以对大肠杆菌有较好的抑菌效果。其中植物乳杆菌QB3-3具有长达96 h的持续抑菌效果。电子显微镜观察显示，植物乳杆菌抗病原菌的主要机理为破坏细胞结构，导致病原菌菌体形态改变，内容物流出，致使细胞死亡。

Antagonistic Mechanism of Lactobacillus plantarum against Foodborne Pathogenic Bacteria

In this study, Oxford cup method was used to screen Lactobacillus plantarum strains with antibacterial effect.
The fermentation supernatants from these strains were either treated with protease or adjusted for pH using NaOH before
being tested for their ability to inhibit the foodborne pathogenic bacteria Escherichia coli O157:H7 and Staphylococcus
aureu. Results showed that organic acid was the major antibacterial compound, yet when adjusted to pH 6.5 the fermentation
supernatants had better inhibition ability against E. coli O157:H7. L. plantarum strain QB3-3 showed antibacterial effect for
up to 96 h. In addition, the antagonistic mechanism of L. plantarum against foodborne pathogens was due to destruction of
the cell structure resulting in morphological changes, leakage of cell contents and finally apoptosis as observed via electron
microscopy.