Production of staphylococcal enterotoxin H under controlled pH and aeration.

The effects of controlled pH and aeration on the growth of Staphylococcus aureus strain FRI-569 and production of enterotoxin H (SEH) were studied. S. aureus FRI-569 did not grow well anaerobically. Aeration permitted better growth of cells especially at a flow rate of 300 cc/min. The optimal pH for S. aureus FRI-569 growth was 7.0, with less growth being observed at pH 6.5 and 7.5 or with no pH control. Very little SEH (< 21 ng/ml) was produced by S. aureus strain FRI-569 under anaerobic incubation. High SEH production was observed with aeration at 300 cc/min. Increasing aeration to 400 cc/min or decreasing it to 200 cc/min resulted in reduced SEH production. Larger amounts of SEH were produced when the pH was controlled at 7.0, while maintaining the pH at 6.5 or 7.5 resulted in lower levels of SEH being produced. However, the amounts were still greater than those observed when the pH was not controlled.