Kombucha is a liquid drink with yellow-amber color and soft-acid cider taste. Kombucha is prepared by the fermentation of a tea-containing liquid by the so-called Kombucha “mushroom.” The term “Kombucha” is synonymous with comboucha, cajnyj kvas (Russian), Kvass, Combuchagetränk (German), Kargasoktee (German), komboecha-drank (Dutch), Kombuchakwass (German), tea-beer, and tea-cider (English) in various culture and languages, Kombucha is believed to have antibiotic properties and nutrients including gluconic acid, vitamins B1, B2, B3, B6, B12, folic acid, and lactic acid D(+). The health benefit of Kombucha is known and appreciated for generations in Eastern Asia, Eastern Europe, and Russia. Kombucha has been tested for the therapeutic effect in Asia and Russia and used as natural therapeutic means. In recent years, Kombucha becomes popular in the United States, and commercially produced Kombucha drinks are widely distributed throughout the country.
The Kombucha “mushroom” refers to a symbiotic mushroom-like cellulose body mainly consisting of yeast, acetobacter, gluconobacter, and sometimes a small amount of lactic acid bacteria Lactobacillus bulgaricum. The bacteria that have been isolated from Kombucha include Acetobacter xylinum, Acetobacter xylinoides, Bacterium gluconicum, Acetobacter ketogenum, Acetobacter suboxydans, Gluconobacter liquefaciens, Acetobacter aceti, and Acetobacter pasteurianus, among which Acetobacter xylinum is the most important. Additionally, yeasts have been isolated from Kombucha, including Saccharomyces cerevisiae, Saccharomyces inconspicus, Saccharomycodes ludwigii, Schizosaccharomyces pombe, Candida tropicans, Candidacrusei, Debaryomyces hansenii, Brettanyomyces, Kloeckera, and Zygosaccharomyces bailii. 
During the conventional fermentation process for making Kombucha, one or more strains of acid bacteria and yeasts form a symbiotic relationship in the fermenting liquid. At the beginning stages of fermentation, yeasts degrade the sugar to glucose and fructose and further ferment them to ethanol, which are supplied to the acetobacters in the culture to reproduce in large quantities. Subsequently, acetobacters oxidize glucose and fructose to gluconic acid and acetic acid, and oxidize ethanol to acetic acid. Some studies show that the ethanol produced by the yeasts stimulate the growth of the acetobacters to produce more cellulose acetate membranes and acetic acid, while acetic acid in turn stimulates the yeasts to make more ethanol. The existence of acetic acid and ethanol protect the acetobacters and yeasts from being infected by other microorganisms. Additionally, the cellulose acetate membranes produced by the acetobacters form the mushroom-like body float on the top of the fermenting liquid and physically support the yeasts and bacteria to allow better exposure to the air and oxygen that are needed for the fermentation.
As the conventional fermentation process for making the Kombucha depends on the combinations of yeasts and bacteria in the culture, the taste, quality, and contents of the Kombucha vary from batch to batch. The inconsistency in the quality of the products has hindered the industrial scale production for Kombucha. Moreover, the conventional fermentation process by using the combination of yeasts and bacteria usually takes about 7 days to 2 weeks, which make the large scale production even more difficult. While the Kombucha mushroom is prod during the fermentation process and reused for making further culture, it eventually tails to make the fermented drink with the same flavor and quality within a months and needs to be constantly replenished by new cultures. Furthermore, the Kombucha may come with a strong acetic or alcohol flavor which deter some consumer from drinking and enjoying the benefits thereof.