原儿茶酸对阪崎克罗诺肠杆菌的抑制作用

【背景】阪崎克罗诺肠杆菌是一种食源性条件致病菌,它能够引起新生儿、婴幼儿及免疫能力低下的成年人罹患多种疾病,致死率高达50%-80%。【目的】探究天然植物源物质原儿茶酸对阪崎克罗诺肠杆菌的抑制作用及可能的抑制机理。【方法】采用琼脂稀释法确定原儿茶酸对阪崎克罗诺肠杆菌的最小抑菌浓度,并检测其对阪崎克罗诺肠杆菌生长曲线的影响。为探究原儿茶酸对阪崎克罗诺肠杆菌细胞膜的损伤,实验测定了细菌胞内pH、膜电位、胞内ATP浓度、细胞膜完整性,并利用扫描电镜观测原儿茶酸对阪崎克罗诺肠杆菌细胞形态的改变。【结果】原儿茶酸对阪崎克罗诺肠杆菌的最小抑菌浓度为2.5-5.0 mg/mL,原儿茶酸降低了阪崎克罗诺肠杆菌的生长速率。原儿茶酸作用后阪崎克罗诺肠杆菌胞内pH降低,细胞膜电位发生超级化/去极化,胞内ATP浓度降低,细胞膜完整性降低,细胞形态发生变化,这说明原儿茶酸改变了细胞膜通透性。【结论】原儿茶酸对阪崎克罗诺肠杆菌具有良好的抑制效果,其可能的抑菌机理是影响细胞膜的通透性及细胞形态。综合考虑原儿茶酸的多种生物活性,它有潜力作为天然抑菌物质在婴幼儿乳粉等其他食品中开发使用。

Antimicrobial activity of protocatechuic acid against Cronobacter sakazakii

Background] Cronobacter sakazakii is an opportunistic pathogen transmitted by food, which affects mainly newborns, infants and immune compromised adults, with reported case fatality rates of 50%?80%. Objective] The aim of this work was to investigate the antimicrobial effect of a natural plant-derived compound protocatechuic acid (PCA), and its effects on cell membrane permeability of C. sakazakii strains. Methods] We determined the Minimum Inhibitory Concentrations (MICs) using agar dilution method, and growth curves were also measured. Changes in intracellular pH, membrane potential, intracellular ATP concentration, membrane integrity and cell morphology were measured to elucidate the cell membrane damage induced by PCA. Results] The experimental results indicated that the MICs of PCA against C. sakazakii strains were 2.5?5.0 mg/mL. PCA decreased growth rate of C. sakazakii and increased the cell membrane permeability of cells, as evidenced by reduction of pHin, occurrence of cell membrane hyperpolarization/depolarization, intracellular ATP concentration decrease, reduction of membrane integrity and changes of cellular morphology in C. sakazakii cells after exposure to PCA. Conclusion] These findings demonstrated that PCA had antimicrobial activity against C. sakazakii. It exerted antimicrobial action partly through causing cell membrane dysfunction and changes in cellular morphology. Considering its antimicrobial properties, together with its well-known nutritional functions, PCA has potential to be developed as a supplement in infant formula or other foods.