L-乳酸、D-乳酸对3种食源性致病菌的抑制作用

选用金黄色葡萄球菌(S.aureus)、大肠杆菌(E.coli ATCC 43889)、福氏志贺菌(Shigella flexneri CMCC 51334)3株常见的食源性致病菌,用于测定L-乳酸、D-乳酸的最小抑菌浓度(minimum inhibitory concentration,MIC)及最小杀菌浓度(minimum bactericidal concentration,MBC),并比较L-乳酸、D-乳酸对3株食源性致病菌抑菌效果差异.结果表明:L-乳酸、D-乳酸对3株食源性致病菌均有不同程度的抑制作用,金黄色葡萄球菌MIC0.1 mg/mL、MBC 3.2 mg/mL,大肠杆菌MIC 0.1 mg/mL、MBC 1.6 mg/mL,福氏志贺菌MIC 0.1 mg/mL、MBC3.2mg/mL.在所选3株指示菌浓度105～106 CFU/mL、乳酸0.2 mg/mL质量浓度下,L-乳酸的抑菌效果显著高于D-乳酸.

Antibacterial Activity of L-and D-Lactic Acid against Three Foodborne Pathogenic Bacteria

Three common foodborne pathogenic bacteria, Staphylococcus aureus, Escherichia coli and Shigella flexneri, were selected for assessing the antibacterial activity of L- and D-lactic acid as indicated by minimum inhibitory concentration （MIC） and minimum bactericidal concentration （MBC）. The growth of all these foodborne pathogens was inhibited in the presence of L- or D-lactic acid. Both showed an MIC of 0.1 mg/mL for all the pathogens and an MBC of 3.2, 1.6 and 3.2 mg/mL for Staphylococcus aureus, Escherichia coli and Shigellaflexneri, respectively. L-lactic acid more significantly inhibited the three indicator strains at a density of 105-106 CFU/mL than its D-isomer when present at a concentration of 0.2 mg/mL.