Kombucha mushrooms are not actually mushrooms but they are cultures, also referred to as SCOBYs, or symbiotic cultures of bacteria and yeast. Typically with each brewing cycle, a new culture, or "baby" mushroom, forms from the "mother" mushroom.
The yeast ferment the sugar to alcohol, and the bacteria convert the alcohol to beneficial acids. Because of the brewing process, kombucha tea has a slight trace of alcohol (<0.5%).
Various factors, including pH, temperature, and time can affect the brew.
Also known as the "elixir of immortality," kombucha is claimed to cure various ailments, such as cancer, and is said to have detoxifying effects and probiotics (beneficial bacteria), which are beneficial to the digestive system.