Antibacterial Activity of Tea Polyphenols against Clostridium botulinum

Studies on Antibacterial Effects of Tea Polyphenols Part II

Abstract

In the previous paper we reported the fate of Clostridium botulinum spores inoculated into tea drinks and postulated that the spore-killing effect of these drinks is due topolyphenolic (tannic) components of tea. In the present experiments, minimum inhibitoryconcentration (MIC) of each tea polyphenolic component against spores and vegetative cells of C. botulinum was determined. As tea polyphenols, "crude catechins" and "crude theaflavins" were separated. These crude substances were further purified into each four catechins and theaflavins. Catechins and theaflavins were mixed at graded concentrations with TGC medium to make the test medium. Spores (5×10²) were mixed with above test media anaerobically in pouches. Vegetative cells were preincubated and streaked on the solidified test medium. All these samples were incubated anaerobically at 30°C for 3 days to find out the growth inhibitory concentrations. As a result, several hundred ppm concentrations of crude catechins, gallated catechins and all theaflavin fractions inhibited the growth of both spores and vegetative cells of C. botulinum, duly supporting the validity of the previous paper. The same experiments were done with some other heat-tolerant bacteria with convincing but unpredictable results.