Water Relations of Staphylococcus Aureus At 30°C

Abstract

Fourteen food-poisoning strains of Staphylococcus aureus have been grown in various media of known water activity at 30°C. Aerobic growth was observed atwater activities between 0.999 and 0.86. The rate of growth and the yield of cells were both reduced substantially when the water activity was less than c. 0.94. The lower limits for growth in dried meat, dried milk, and dried soup were similar to those in liquid media. Aerobic growth proceeded at slightly lower water activities than anaerobic growth. All cells were capable of forming colonies on agar media with water activities as low as 0.92. The 14 strains proved to be a homogeneous group with similar water equirements.