Characteristics of Staphylococcal Enterotoxin A Production and Growth of Staphylococcus aureus in Shaking and Stationary Cultures

摘要

Staphylococcal food poisoning, which is still a serious health problem worldwide, is caused by staphylococcal enterotoxin (SE). Among many types of SE, staphylococcal enterotoxin type A (SEA) is known to be the most responsible for staphylococcal food poisoning. Production by SEA-producing strains in shaking culture has been studied by many investigators, whereas the kinetical differences between shaking and stationary cultures have not been studied intensively. Therefore, this difference was studied at various temperatures from 14 degrees C to 46 degrees C in the present study. Consequently the maximum SEA concentration and populations of SEA producer in shaking culture was higher than those in stationary culture. Of interest, however, the productivity, which is the maximum SEA amount produced by one cell, in shaking cultures was lower than that in stationary culture. Kinetic analysis clarified that SEA gene expression in staphylococcal cells preceded toxin production at optimal temperature. Next, several SEA producers were studied for the maximum toxin production at various temperatures from 14 degrees C to 42 degrees C in shaking culture. Consequently all strains showed different patterns, suggesting that the characteristics of SEA production of these strains would be strain-specific. These results in this study would provide useful, basic information to prevent staphylococcal food poisoning outbreaks.