Effect of water activity on enterotoxin A production and growth of Staphylococcus aureus.

Previous studies indicated that enterotoxin B production by staphylococci was strongly inhibited by slight reductions in water activity (a(w)) levels. Similar studies reported herein, employing an enterotoxin A-producing strain, indicated that this organism was capable of producing enterotoxin at a much lower a(w) level than that required for enterotoxin B production. Staphylococcal growth rates were slowed by decreased a(w) levels in all media tested; however, final cell counts did not drop below 10(8)/ml in the media with the lowest a(w) levels.