乳酸链球菌素(Nisin)抑菌作用及其抑菌机理的研究

Study on antibacterial function and mechanism of Nisin

通过抑菌试验确定了乳酸链球菌素(Nisin)的高产菌株-乳酸乳球菌乳酸亚种T0625菌株的抑菌谱。结果显示,含有乳酸链球菌素的发酵液对革兰氏阳性细菌有抑制作用,但对革兰氏阴性细菌、酵母菌和霉菌无抑制作用。从T0625菌株发酵液中提取乳酸链球菌素加入金黄色葡萄球菌培养液中进行抑菌试验,结果培养液蛋白质含量提高、电导率增加,未出现对数生长期。透射电镜观察发现,加入乳酸链球菌素后,菌体变形,出现质壁分离现象,进而菌体细胞破裂,细胞内容物大量外泄,菌体成为不规则残片。SDS-PAGE凝胶电泳显示,乳酸链球菌素作用使金黄色葡萄球菌菌体内蛋白质减少,培养液中蛋白质增加。推测乳酸链球菌素的作用位点为细胞膜,具有破坏菌体细胞膜完整性的作用。试验结果支持了"孔道形成"理论的观点。

The antibacterial spectrum of a Nisin-producing strain, Lactococcus lactis sub. Lactis T0625, was confirmed by antibacterial tests. The results showed that the fermention broth containing Nisin showed inhibition to gram-positive bacteria, but non-inhibition to gram-negative bacteria, yeast and mould. Nisin was extracted from T0625 fermentation broth, and added into Staphylococcus aureus broth to test the inhibition effect. The re suits showed that the protein content and conductivity of Staphylococcus aureus broth increased, and the exponential phase of growth did not appear. By the observation under the transmission electron microscope, it was founded that Nisin extract made the cell distorted and plasmolysis, followed by cell broken and cell components releasing which turned the cell into irregular residues. SDS-PAGE electrophoresis showed that the content of protein decreased in Staphylococcus aureus under Nisin extract treatment, in contrast, the content of protein in the broth increased. It can be hypothesized that the action site of Nisin was cell membrane, whose integrity was damaged by Nisin. The results supported the viewpoint of＂Pore Formation＂.