Characterization of water-types and their influence on the antimicrobial proper-ties of Kombucha ferments against bacteria and yeast

Abstract

Understanding the relationships between diet, gut microflora, and health is an increasingly important area of research. Recent studies have demonstrated that Kombucha tea provides variable antimicrobial activity against pathogenic microbes. In this study, we tested Kombucha tea for antimicrobial activity against various Gram-positive and Gram-negative bacteria, as well as yeast, using an agar diffusion method. Standard zone of inhibition assays were used to test the hypothesis that variance in antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans may be due to the varying levels of cations, like Ca2+, found in different water-types (well water, artesian water, city water, type-II water and distilled water). Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) results indicated that high cationic (Ca2+, Mg2+, and Na+) content water (well water) resulted in the largest zone of inhibition against S. aureus, with a 12.3% difference when compared to low cationic content water (type-II water). E. coli maintained a constant zone of inhibition regardless of water-type or batch-type, while C. albicans showed no zones of inhibition. Inhibition is either through a synergistic relationship with the pH conditions, the other cations present (Mg2+, Na+, Si, etc.) or a mix of both, as pH in the range of 4.5 - 3 is not enough to inhibit the growth of S. aureus. These results indicate that a direct relationship exists between cationic concentrations of water used to prepare Kombucha, and antibacterial activity against S. aureus, due to the improved fermentation of the tea with high concentrations of cations. Strong antimicrobial potential exists, particularly against S. aureus, which may be useful in determining novel approaches to synthesize antimicrobial drugs. Further study is needed to assess other S. aureus strains, as well as to determine how this relationship translates to human microbiota interactions and their microbial metabolic profiles.