Q: How do you grow a thick kombucha mushroom?
A: Remember that Kombucha Mushrooms Come in All Shapes, Sizes, and Colors! Even if your kombucha mother does not look like a perfectly even 1/8 - 1/2 inch thick cream-colored pancake, it could still ferment your kombucha very well!
If you want a thick kombucha mother, you can put some kombucha in a clean glass jar, cover it well with a breathable cloth, and let it sit for a few weeks until a thick mother grows and develops. Or, you can just let one of your kombucha brews ferment for a prolonged period of time until a thick SCOBY forms.
The kombucha will become pretty strong, sour, and acidic if it has been fermenting for a long time, and using this kombucha as starter tea will favor the bacteria and thick SCOBY formation (1). For other uses of sour kombucha, check out Happy Herbalist's recommendations: Kombucha Tea Too Sour?
Acetobacter xylinum has been indicated to be one of the main bacteria in the colony that helps to form the cellulose structure of the kombucha mushroom (2-3). So to favor a thick kombucha mother, you want to favor the bacteria.
For more information on decreasing yeast to bacteria ratios, which will favor the bacteria and a thick SCOBY, visit Kombucha Balance: Decreasing the Ratio of Yeast to Acetobacter Populations.
1. Kombucha Balance: Decreasing the Ratio of Yeast to Acetobacter Populations2. Greenwalt, C.J., R.A. Ledford, and K.H. Steinkraus. "Determination and characterization of the anti-microbial activity of the fermented tea Kombucha." Lebensmittel-Wissenschaft und-Technologie 31 (3) (1998): 291-296.3. Malbasa, R., E. Loncar, and M. Djuric. "Comparison of the products of Kombucha fermentation on sucrose and molasses." Food Chemistry. 106 (2008): 1039-1045.