金黄色葡萄球菌耐盐生长的形态观察及机理的初步研究

 为阐明金黄色葡萄球菌特有的耐盐生长特性的机理，试验将该菌分别培养于含低盐（1.0％NaCl）和高盐（10.0％NaCl）的LB液体培养基及卵黄琼脂培养基，观察发现高盐液体条件下该菌呈絮状生长，细菌个体形态明显增大，在高盐固体条件下菌落形态较小，菌落形成单位（CFU）数量也明显减少；对菌体裂解产物进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析，发现金黄色葡萄球菌在高盐与低盐培养条件下的蛋白表达谱存在差异，前者比后者被诱导多表达出至少一个蛋白质条带（MW 22ku）；将相同数量的该菌接种于含05IU/mL青霉素作为细胞壁合成抑制剂及不同氯化钠浓度（1.0%，2.5%，4.0%，5.5%，7.0%，8.5%和10.0%）的卵黄琼脂培养基上培养，发现随着NaCl浓度的升高，CFU数量逐渐减少。结果表明，金黄色葡萄球菌的耐盐生长特性与其细胞壁合成和盐应激蛋白表达有关，并伴随有菌落、菌体形态的变化。

Morphological Observation and Pilot Study on Growth Traits of Staphylococcus aureus under High-salt Condition

In order to understand mechanisms for peculiar salt tolerant growth property of Staphylococcus aureus, the bacteria were separately cultured in Luria Bertani (LB) liquid medium as well as egg yolk agar medium containing low salt (1.0% NaCl) or high salt (10.0% NaCl), and it was found that the former grew in a flocculent manner and had a bigger body size in the liquid medium, and showed smaller colony size and produced less colony forming units (CFUs) in the solid medium; the cell lysates from the bacterial cultures were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE), resulting in discrepancy of electrophoretic patterns of proteins, namely, at least one more protein band (MW 22 ku) inductively expressed in the high salt bacterial culture; the bacteria were also cultured on egg yolk agar medium with a final concentration of 0.5 IU/mL penicillin as an inhibitor for cell wall synthesis and different NaCl concentrations (1.0%, 2.5%, 4.0%, 5.5%, 7.0%, 8.5% and 10.0%), and it turned out that the counting of CFUs decreased with the increase of NaCl concentrations. The findings above demonstrated that intact cell wall and the salt inducible protein contributed to the salt tolerance of S. aureus, which in turn made its colonial and individual shapes change.