Table 4. Antibacterial activities of KWL

Target miroorganism Testing materials
Acetic acid (7.6 g/L) Unfermented tea Fermented tea (Kombucha)
pH 4.0 pH 7.0 0 days 1 days 4 days 7 days
Staphylococcus aureus (KCTC 3881, Korea) ++ Heat-denatured + ++
Natural pH + + ++
Bacillus cereus (KCTC 362A, Korea) + Heat-denatured
Natural pH
Escherichia coli (KCTC 1682, Korea) ++ Heat-denatured ++ ++ +++
Natural pH + +++ +++
Salmonella enterica (KCTC 2054, Korea) + Heat-denatured + + ++
Natural pH + ++ +++
All values were mean±SD of triplicates.
The diameters of the clear zone of inhibition were as follows: –, no inhibition; +, 10≤diameter≤15; ++, 15≤diameter≤20; +++, 20≤diameter≤25 (mm); Acetic acid, acetic acid concentration of Kombucha (7.6 g/L); Unfermented tea, 1 M HCl or 1 M NaOH was used to adjust their pH; Heat-denatured: 100°C, 5 min; Natural pH: pH value of the sample without any adjustment.