百里酚和香芹酚对阪崎克罗诺肠杆菌的抑制作用

为探究百里酚和香芹酚对阪崎克罗诺肠杆菌的抑制作用及机理。测定百里酚、香芹酚对阪崎克罗诺肠杆菌最小抑菌浓度(MIC),研究两种物质对阪崎克罗诺肠杆菌生长曲线、膜电位、胞内pH、胞内ATP、细胞膜完整性的影响,利用场发射扫描电镜观测细胞形态的变化。结果表明:百里酚和香芹酚对阪崎克罗诺肠杆菌具有良好的抑制作用,两者对9株阪崎克罗诺肠杆菌的最小抑菌浓度均在0.1~0.2 mg/mL之间。百里酚和香芹酚均可使阪崎克罗诺肠杆菌细胞膜出现超极化,浓度为4MIC的百里酚和香芹酚分别使菌株的胞内pH由5.45降低至4.96和4.97,胞内ATP浓度由0.584降低为0.048和0.027 μmol/L,细胞膜完整性分别下降85.0%和88.1%。场发射扫描电镜结果显示,百里酚和香芹酚均能够导致菌体出现干瘪皱缩,细胞膜出现孔洞甚至裂解。结果显示,百里酚和香芹酚对阪崎克罗诺肠杆菌均具有良好的抑制效果,其作用机理可能与细胞膜的通透性及细胞形态有关。百里酚和香芹酚虽然互为同分异构体,但二者对阪崎克罗诺肠杆菌的抑制作用并未表现出明显的规律性差异。

Inhibitory Activity of Thymol and Carvacrol Against Cronobacter sakazakii

This study was aimed to determine the antimicrobial effects and mechanisms of thymol and carvacrol against C.sakazakii.The minimum inhibitory concentration (MIC) of thymol and carvacrol against C.sakazakii were first determined. Effects of two substances on growth curves, membrane potential, intracellular pH, and intracellular ATP and membrane integrity of C.sakazakii were also measured.Cell morphology changes were observed under field emission scanning electron microscope. The results showed that both thymol and carvactol had a good antimicrobial effect on C. sakazakii, the MICs of thymol and carvacrol against C.sakazakii strains ranged from 0.1 to 0.2 mg/mL.The membrane of cells treated with thymol and carvacrol became hyperpolarized.In addition, thymol and carvacrol of 4MIC caused a decrease in pH_in of C.sakazakii from 5.45 to 4.96 and 4.97, and also made intracellular ATP concentrations reduce from 0.584 to 0.048 and 0.027 μmol/L, respectively.4MIC thymol and carvacrol also caused 85.0% and 88.1% reduction in cell integrity of C.sakazakii.Field emission scanning electron microscopy showed that both thymol and carvacrol could cause more wrinkled surface of the cells, and pores and even cracks in the cell membrane.The research demonstrated that carvacrol and thymol had strong inhibitory effect on C.sakazakii, which was possibly due to cell membrane dysfunction and changes in cellular morphology.However, the antimicrobial effects of these two natural substances showed no significant differences.