| Abstrak/Abstract |
Staphylococcus species in food produce Staphylococcal enterotoxins (SEs)
that cause Staphylococcal food poisoning (SFP). More than 20 SE types have been
reported, among which Staphylococcal enterotoxin A (SEA) has been recognized as one
of the most important SEs associated with SFP. However, the regulatory mechanisms
underlying its production remain unclear. Previously, we identified a major SFP clone in
Japan, CC81 subtype-1, which exhibits high SEA production. In this study, we attempted
to identify the factors contributing to this phenomenon. Thus, we demonstrated that the
attenuation of the activity of endogenous regulator, Staphylococcal accessory regulator
S (SarS), and the lysogenization of a high SEA-producing phage contributed to this
phenomenon in CC81 subtype-1. Furthermore, our results indicated that SarS could
directly bind to the promoter upstream of the sea gene and suppress SEA expression;
this low SarS repression activity was identified as one of the reasons for the high SEA
production observed. Therefore, we revealed that both exogenous and endogenous
factors may probably contribute to the high SEA production. Our results confirmed that
SE production is a fundamental and critical factor in SFP and clarified the associated
production mechanism while enhancing our understanding as to why a specific clone
frequently causes SFP. |
