An example of mixed pure bacterial culture fermentation is yogurt fermentation, which typically uses Streptococcus thermophilus and Lactobacillus bulgaricus. The interactions are commensal. Figure 3 illustrates the development of acidity of pure and mixed cultures of S. thermophilus and L. bulgaricus in liquid. In mixed cultures, S. thermo-philus grows faster at the beginning, reduces the pH by lactic acid production, and also produces formic acid, which is a stimulatory compound for L. bulgaricus. L. bulgaricus produces amino acids that stimulate the growth of S. ther-
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Discover How To Become Your Own Brew Master, With Brew Your Own Beer. It takes more than a recipe to make a great beer. Just using the right ingredients doesn't mean your beer will taste like it was meant to. Most of the time it’s the way a beer is made and served that makes it either an exceptional beer or one that gets dumped into the nearest flower pot.