Effects of Nutritional Conditions on Growth, Biofilm Formation, and Enterotoxin Production in Staphylococcus aureus Associated with Food Poisoning.

Staphylococcal food poisoning (SFP) is a common foodborne illness caused by the ingestion of enterotoxins produced by Staphylococcus aureus, posing a persistent global public health concern. Although regional differences in implicated food types and predominant enterotoxins have been reported, the underlying factors remain unclear. In this study, we systematically investigated the effects of nutritional factors on the growth, biofilm formation, and production of two representative enterotoxins, SEA and SEB, by S. aureus. Specifically, we evaluated bacterial responses to different concentrations of NaCl, glucose, and tryptone. NaCl suppressed growth, biofilm formation and enterotoxin production in a dose-dependent manner. Glucose markedly inhibited both bacteria growth and enterotoxin production, with a stronger effect on SEB than SEA. In contrast, tryptone promoted bacterial growth and moderately enhanced biofilm formation but did not significantly affect enterotoxin production. Importantly, even under comparable bacterial counts, the types and amounts of SEs produced varied substantially depending on the nutrient composition. These findings provide new insights into the nutrient-dependent regulation of virulence in S. aureus and highlight the importance of considering environmental and nutritional factors when assessing risks of SFP and designing effective food safety strategies.