Bactericidal Activity of a Fermented Hot-Water Extract from Stevia rebaudiana Bertoni towards Enterohemorrhagic Escherichia coli O157:H7 and Other Food-Borne Pathogenic Bacteria

抄録

A fermented aqueous extract from Stevia rebaudiana Bertoni showed strong bactericidal activity towards a wide range of food-borne pathogenic bacteria including enterohemorrhagic Escherichia coli O157:H7. The colony-forming ability of the food-borne pathogenic bacteria tested so far was reduced to <10^-7 when exposed to ≥40% (v/v) solutions of the fermented extract at 37C for 2hr. Secretion of verocytotoxin 1 and 2 by enterohemorrhagic E. coli was also diminished by fermented extract at a concentration of ≥10% (v/v). In contrast, the fermented extract did not significantly kill Bifidobacteria or Lactobacilli. The active principle(s) of the fermented Stevia extract were bactericidal under acidic conditions.