INFLUENCE OF PROTEIN SUPPLEMENTS ON GROWTH OF Staphylococcus aureus AND PRODUCTION OF ENTEROTOXINS

Abstract

ABSTRACTInfluences of soy protein (promine D; SP), fish protein concentrate (FPC) and Brewer's Yeast or Torula Yeast on aerobic growth of S. aureus (288) and production of enterotoxins A and D were evaluated in liquid media containing equivalent amounts (1.8%) of protein from each source. S. aureus grew faster (29 min generation time) and reached a final population of 2–7 × 109/ml in yeast media as compared to soy or, fish protein concentrate; 50–56 mm generation time and a final population of 2 × 108/ml in SP or EPC. Production of enterotqxins by S. aureus was enhanced in yeast media. Enterotoxin A was detectable in unconcentrated yeast preparations after 6 hr and both toxins (A and D) after 12 hr incubation. Enterotoxin A was detected only in FPC concentrated 50‐fold and after 24 hr incubation. Neither enterotoxin A nor D was detected in SP concentrated 100‐fold after 24 or 48‐hr incubation. Addition of Brewer's Yeast (2% w/v) to whole milk enhanced production of enterotoxins A and D; there was at least a 100‐fold higher amount of enterotoxin in milk + yeast as compared to simply milk.