山楂果胶寡糖的抑菌性能及机理

Antibacterial Activity and Mechanism of Hawthorn Pectin Oligosaccharides

采用抑菌圈法对不同聚合度的山楂果胶寡糖进行选择,测定了实验样品对5种供试菌的最小抑菌浓度(minimal inhibitory concentration,MIC)和最小杀菌浓度,绘制了供试菌的生长曲线来评定样品的抑菌效果;并从菌体形态、胞膜通透性、胞膜完整性等方面阐述果胶寡糖抑菌的机理。结果表明:平均聚合度为3的果胶寡糖对供试菌种的抑菌效果最为显著,尤其是对大肠杆菌、枯草芽孢杆菌和金黄色葡萄球菌3种供试菌的抑菌效果最为明显,其MIC值分别为1.250、0.625、0.625 g/L。随着加入果胶寡糖质量浓度的增大,菌悬液的相对电导率也随之升高,同时菌悬液中核酸和蛋白质含量增大,由此表明果胶寡糖的抑菌性能是由于其破坏了细菌胞膜的通透性和完整性,致使内容物外漏进而影响其代谢活性,抑制细菌生长。因此山楂果胶寡糖可以作为天然防腐剂,抑制食品中腐败菌和致病菌的生长,延长食品货架期。

In this study we conducted experiments to determine the minimal inhibitory concentration（MIC） and minimal bactericidal concentration（MBC） of hawthorn pectin oligosaccharides with different polymerization degrees, and to draw the growth curves of five test strains in order to explore the antibacterial activity of pectin oligosaccharides. The underlying mechanism was elucidated by evaluating the changes in cell morphology, cell membrane permeability and integrity. The results showed that pectin oligosaccharides with average polymerization degree of 3 had the strongest antibacterial effect, especially against Escherichia coli, Bacillus subtilis and Staphylococcus aureus, with MICs of 1.250, 0.625 and 0.625 g/L, respectively. The relative conductivity of bacterial cell suspensions increased with increasing addition of pectin oligosaccharides, accompanied by a simultaneous increase in nucleic acid and protein concentrations, implying that pectin oligosaccharides exerted antibacterial activity presumably by damaging the cell membrane permeability and integrity and consequently resulting in leakage of cell contents, thereby causing an adverse effect on the metabolic activity and consequently inhibiting bacterial growth. Therefore, hawthorn pectin oligosaccharides can be used as natural preservatives to inhibit the growth of spoilage bacteria and pathogens in foods and thus prolong their shelf life.