Repair, Growth, and Enterotoxigenesis of Staphylococcus aureus S-6 Injured by Freeze-Drying

Abstract

Staphylococcus aureus S-6 cells in the mid-log growth phase rapidly (0.5–1 h) repaired freeze-drying injury when rehydrated at mesophilic temperatures (20–50 C), although these temperatures had a greater effect on subsequent growth of total survivors. At 15 C repair and growth processes were slow. At 10 C repair and growth did not occur. Enterotoxin B was released into the rehydration medium at about the time when survivors initiated growth but was difficult to demonstrate during the repair stage because of the short duration of this phase. Metabolic and macromolecular inhibitor studies on S. aureus S-6 cells injured by freeze-drying suggested that RNA synthesis was necessary as the first stage of repair.