Yeast

 http://www.zeiss.com/C12567BE00472A5C/GraphikTitelIntern/Yeast-TimelapsePopUp/$File/Yeast-TimelapsePopUp.jpg

             Saccharomyces boulardii is not a bacteria , is a yeast which is a type of fungus. Most yeasts are used for baking bread or brewing beer. S. boulardii on the other hand, treats diahrea. One other particular bacteria called saccharomyces cerevisiae helps bread dough rise so you can bake it. It does this by fermenting different sugars like glucose, fructose, maltose, and sucrose.

This is a short video of yeast making bread rise.

http://www.youtube.com/watch?v=MNQXoqFKxdY&feature=related