Inhibitory Effects of Cholate and Sodium Chloride on the Growth of Staphylococcus aureus

Though the concentration of sodium chloride in salt-tolerance of Staphylococcus aureus was approximately 15%, the bacterial cells survived in the medium containing 18% sodium chloride for 10 days. They were able to grow in the presence of 0.1% cholate, but no appreciable growth was observed in the presence of 0.2% cholate. However, they survived in the presence of 0.5% cholate for 10 days.The salt-tolerance of the cells lowered markedly in the presence of cholate, e. g., the salt-tolerance fell to 4, 3, 2, 1% and below 1% in the presence of 0.05, 0.06, 0.07, 0.08 and 0.09% cholate, respectively. When the cells were heated at 55°C for 10min in the presence of 0.05% cholate and 3% sodium chloride, cooled by running water, frozen in a freezer at -20°C, allowed to stand for a few weeks and thawed in an incubator controlled at 30°C, they suffered fatal damage and the growth lagged for several days, compared with the growth of native cells.The synergistic effects of cholate and sodium chloride on the growth were strongly enhanced by heating and freezing of the cells.