SCOBY

A SCOBY (for symbiotic colony of bacteria and yeast), or kombucha mother, is a mix of cultures of bacteria and yeast present during production of kombucha. The term "colony" in the name is a scientific misnomer, because it implies a group of genetically identical or nearly identical organisms living together. For this reason, the acronym is essentially absent in the biomedical literature and the proper name pellicle is used. The species comprising the mixed cultures vary from preparation to preparation, but generally include Acetobacter bacterial species, as well as various Saccharomyces and other yeast types. SCOBY cultures used in beverage production can produce a structure referred to as a mushroom, which is also biologically misleading, because mushrooms are a completely unrelated group of fungi. It often forms in vinegar in jars of pickled foods.

Composition

File:SCOBY mushroom.jpg

A SCOBY used for brewing kombucha, made up of Acetobacter species of bacteria, and undefined yeast species.

Yeast and bacteria commonly found in SCOBY include:

• Acetobacter spp.: a collection of aerobic bacterial species producing acetic acid and gluconic acid, always found in Kombucha cultures, including Acetobacter ketogenum (see below for the related Gluconacetobacter species), and contributing to the SCOBY "mushroom";
• Saccharomyces spp.: a number of aerobic or anaerobic yeast species producing alcohol, the most common of yeasts in Kombucha cultures, including S. ludwigii, S. apiculatus, and S. cerevisiae;
• Schizosaccharomyces pombe: a yeast species, commonly called "fission yeast";
• Brettanomyces spp.: aerobic or anaerobic strains commonly found in Kombucha cultures producing either alcohol or acetic acid;
• Lactobacillus: aerobic bacteria sometimes but not always found in Kombucha cultures, producing lactic acid and slime;
• Pediococcus spp.: anaerobic bacteria producing lactic acid and slime, sometimes, but not always found in the Kombucha culture;
• Gluconacetobacter xylinus: anaerobic bacteria that ferments alcohols produced by the yeasts, producing acetic and other acids, increasing the drink's acidity and limiting ethanol content;
• Gluconacetobacter kombuchae: an anaerobic bacteria unique to kombucha that feeds on nitrogen compounds in tea, producing acetic and gluconic acids, and building the SCOBY "mushroom";
• * Zygosaccharomyces spp.: including Zygosaccharomyces kombuchaensis, a yeast strain that is unique to Kombucha cultures, producing alcohol and carbonation and contributing to the SCOBY "mushroom."

Use in food production

Other foods and beverages which require a similar "symbiotic culture" in their production include:

• Ginger beer;
• Kefir, both milk kefir and water kefir (tibicos), whose required cultures differ;
• Jun; a drink similar to kombucha that grows on honey-sweetened green tea;
• Vinegar; the production of which requires a mother of vinegar; and
• Sourdough; derived from a sourdough "starter," flour-water mixture exhibiting growth after advantitious contamination with wild yeasts.

See also

• Kombucha
• Lactic acid bacteria
• Acetic acid bacteria

Further reading

• Program entitled "The Fermentation Revival" on BBC News.
• N. Padilla "do it yourself article in the The Harvard Crimson.

Outside links

• Purported list of kombucha yeast and bacteria, at "Cultures for Health."

References

References

[1]... http://www.bbc.co.uk/iplayer/episode/b01g4ks7/Food_Programme_The_Fermentati... available online via public BBC-iplayer to 2099