[7] Although the SCOBY is commonly called "tea fungus" or "mushroom", it is actually "a symbiotic growth of acetic acid bacteria and osmophilic yeast species in a zoogleal mat [biofilm]".

[20] With rising popularity in developed countries in the early 21st century, kombucha sales increased after it was marketed as an alternative to beer and other alcoholic drinks in restaurants and pubs.

[22] English speakers may have confused the Japanese word konbucha with kōcha kinoko (紅茶キノコ, 'black tea mushroom'), popularized around 1975.

[25] Merriam-Webster's Dictionary suggests kombucha in English arose from misapplication of Japanese words like konbucha, kobucha 'tea made from kelp', konbu, from kobu 'kelp', + cha 'tea'.

[26] The American Heritage Dictionary notes the term might have originated from the belief that the gelatinous film of kombucha resembled seaweed.

[27] The first known use in the English language of the word to describe "a gelatinous mass of symbiotic bacteria (as Acetobacter xylinum) and yeasts (as of the genera Brettanomyces and Saccharomyces) grown to produce a fermented beverage held to confer health benefits" was in 1944.

[1] There is a broad spectrum of yeast species spanning several genera reported to be present in kombucha culture including species of Zygosaccharomyces, Candida, Kloeckera/Hanseniaspora, Torulaspora, Pichia, Brettanomyces/Dekkera, Saccharomyces, Lachancea, Saccharomycoides, Schizosaccharomyces, Kluyveromyces, Starmera, Eremothecium, Merimbla, Sugiyamaella.

[32][citation needed] The population of bacteria and yeasts found to produce acetic acid has been reported to increase for the first 4 days of fermentation, decreasing thereafter.

[33] K. xylinus produces bacterial cellulose, and is reportedly responsible for most or all of the physical structure of the "mother", which may have been selectively encouraged over time for firmer (denser) and more robust cultures by brewers.

[42] The container is covered with a paper towel or breathable fabric to prevent insects, such as fruit flies, from contaminating the kombucha.

[43] In 2010, elevated alcohol levels were found in many bottled kombucha products, leading retailers including Whole Foods to pull the drinks from store shelves temporarily.

[1][8][54][55] In a 2003 review, physician Edzard Ernst characterized kombucha as an "extreme example" of an unconventional remedy because of the disparity between implausible, wide-ranging health claims and the potential risks of the product.

[10] The American Cancer Society said in 2009 that "serious side effects and occasional deaths have been associated with drinking Kombucha tea.

[14][29] Adverse effects associated with kombucha consumption may include severe hepatic (liver) and renal (kidney) toxicity as well as metabolic acidosis.

[56][57][58] Some adverse health effects may arise from the acidity of the tea causing acidosis, and brewers are cautioned to avoid over-fermentation.

[61] A 2019 review enumerated numerous potential health risks (including hyponatremia; lactic acidosis; toxic hepatitis, etc.,[55]: 68 ) but said "kombucha is not considered harmful if about 4 oz [120 mL] per day is consumed by healthy individuals; potential risks are associated with a low pH brew leaching heavy metals from containers, excessive consumption of highly acidic kombucha, or consumption by individuals with pre-existing health conditions.

[62][63] Kombucha culture, when dried, becomes a leather-like textile known as a microbial cellulose that can be molded onto forms to create seamless clothing.