Microbial Composition, Bioactive Compounds, Potential Benefits and Risks Associated with Kombucha: A Concise Review

Kombucha is a fermented tea beverage containing bioactive compounds from tea and vital compounds such as acetic acid, D-saccharic acid-1,4-lactone, and glucuronic and gluconic acids produced from the metabolic activities of bacteria and yeasts, which benefit human health. Kombucha contains a symbiotic culture of bacteria and yeast (SCOBY), which actively ferments sugar. Kombucha microbial compositions vary due to environmental conditions and the starter culture. Saccharomyces sp., Schizosaccharomyces pombe, Schizosaccharomyces sp., and Brettanomyces sp. (yeasts) and Acetobacter aceti, Komagataeibacter xylinum (formerly known as Gluconacetobacter xylinum), Gluconobacter oxydans, and Acetobacter pasteurianus (acetic acid-producing bacteria) are commonly found in kombucha. This review focused on the microbial compositions of kombucha and their functionality. Aspects discussed include: (i). developments in kombucha, (ii). microbial compositions of kombucha, (ii). microbial production of kombucha cellulose, (iv). factors influencing kombucha microbial compositions, (v). tea type and kombucha bioactive compounds, (vi). kombucha health benefits, and (v). potential risk factors of kombucha consumption. Current gaps, recommendations, and prospects were also discussed. Kombucha production using rooibos as the tea base is recommended, as rooibos is caffeine-free. Upcycling kombucha wastes, mainly SCOBY, for producing cellulose filters, improving food flavors and as a substrate in food fermentations is touched on.