抑制变形杆菌的干酪乳杆菌LDJ主要抑菌物质分析

Inhibition of Proteusbacillus vulgaris by Main Antibacterial Substances in Lactobacillus casei LDJ

干酪乳杆菌LDJ是一株能抑制变形杆菌生长的优良菌株。为了探究干酪乳杆菌LDJ无细胞上清液的抑菌效果,采用牛津杯法测定了不同培养时间的无细胞上清液对变形杆菌的抑菌能力,发酵时间在0~4 h时无细胞上清液无抑菌能力,发酵至8 h时抑菌能力逐步上升,发酵时间在24~48 h时无细胞上清液抑菌能力趋于平稳;其中,发酵时间在36 h时,抑菌圈直径最大,为20.48 mm。干酪乳杆菌LDJ无细胞上清液中抑菌物质的理化特性研究结果表明:该抑菌物质对大肠杆菌,金黄色葡萄球菌和李斯特菌都有不同程度的抑制作用;无细胞上清液经40~100℃处理30 min,仍有良好的抑菌活性;pH值在3~6范围内抑菌物质有良好的抑菌效果,在中性及碱性条件下则没有抑菌作用;不同酶处理对无细胞上清液的抑菌效果有不同程度的影响。因此,推测其抑菌有效成分可能为肽类及有机酸。

Lactobacillus casei LDJ is an excellent strain that can inhibit the growth of Proteusbacillus vulgaris.To investigate the antibacterial effect of the cell-free supernatant of Lactobacillus casei LDJ,the antibacterial ability of cell-free supernatant with different fermentation time on Proteusbacillus vulgaris was tested by the Oxford cup method.When the fermentation time was 0–4 h,the cell-free supernatant had no antibacterial ability.The antibacterial ability increased gradually after fermentation of 8 h and tended to be stable when fermentation time was 24–48 h.Specifically,when the fermentation time was 36 h,the diameter of the antibacterial zone was the largest(20.48 mm).The research on physicochemical properties of the antibacterial substances in the cell-free supernatant of Lactobacillus casei LDJ shows that the antibacterial substance has various inhibitory effects on Escherichia coli,Staphylococcus aureus,and Listeria monocytogenes.The cell-free supernatant still has good antibacterial activity after treatment at 40–100℃ for 30min.The antibacterial substance has a good antibacterial effect in the range of pH value 3–6 but shows no antibacterial effect under neutral and alkaline conditions.Different enzyme treatments have different effects on the antibacterial effect of cell-free supernatant.Therefore,it is speculated that the effective antibacterial components of Lactobacillus casei LDJ may be peptides and organic acids.