Xiong Z, Ge S, Chamberlain N R, Kapral F A
Department of Medical Microbiology and Immunology, Ohio State University, Columbus 43210.
J Med Microbiol. 1993 Jul;39(1):58-63. doi: 10.1099/00222615-39-1-58.
Three Staphylococcus aureus strains (303, 18Z and TG), exhibiting various patterns of survival within abscesses, were significantly more sensitive to the bactericidal activity of oleic acid during the log phase of growth than at other stages of the growth cycle. Cells entering the stationary phase showed diminished sensitivity to the fatty acid. These changes were reflected by changes in the LD50 and also by differences in the rate of killing by oleic acid. Additional changes were noted: the rate of killing by oleic acid declined over a 4-day period; a progressively greater proportion of the staphylococcal population became resistant to even high concentrations of oleic acid; from the fourth day onwards c. 50-55% of the cocci were totally resistant to the fatty acid. Strains 303 and 18Z became more sensitive to mono-olein during the log phase of growth, but strain TG was very resistant to mono-olein throughout the growth cycle. Growth in the presence of glycine 6% to reduce cross-links in the peptidoglycan did not alter bacterial sensitivity to oleic acid. However, all three S. aureus strains exhibited significant increases in membrane fluidity during the log phase of growth, but upon entering the stationary phase membrane fluidity again decreased. Concomitant changes in carotenoid content occurred during the growth cycle, but these changes did not appear to be solely responsible for the changes in sensitivity to the lipids.
三株金黄色葡萄球菌菌株（303、18Z和TG）在脓肿内呈现出不同的存活模式，在生长对数期比在生长周期的其他阶段对油酸的杀菌活性更为敏感。进入稳定期的细胞对脂肪酸的敏感性降低。这些变化通过半数致死剂量（LD50）的变化以及油酸杀菌速率的差异得以体现。还观察到其他变化：油酸的杀菌速率在4天内下降；葡萄球菌群体中对高浓度油酸产生抗性的比例逐渐增加；从第四天起，约50 - 55%的球菌对脂肪酸完全耐药。菌株303和18Z在生长对数期对甘油单油酸酯更为敏感，但菌株TG在整个生长周期对甘油单油酸酯都具有很强的抗性。在6%甘氨酸存在下生长以减少肽聚糖中的交联，并未改变细菌对油酸的敏感性。然而，所有三株金黄色葡萄球菌菌株在生长对数期膜流动性都显著增加，但进入稳定期后膜流动性又再次降低。在生长周期中类胡萝卜素含量伴随发生变化，但这些变化似乎并非对脂质敏感性变化的唯一原因。
