Yeast, lactic acid and vinegar bacteria from soup naturally deliver soup to bread, breaking down gluten and other anti-nutrients. Current observation of 500 yeast cultures from four different continents has revealed the extent of microbial diversity of this ancient fermented food in different cultural and geographic contexts. A comparison of the microbial diversity of 500 fermented yeast cultures from around the world and from 4 different continents yielded striking results. The presence of acetic acid in the sourdough bacteria had a strong effect on the aroma and flavor of the bread. The action of beneficial bacteria and yeast in the dough, including the production of organic acids and extracellular enzymes, also affects the taste, texture and shelf life of the bread. Soup dough bakers can make their own flour and freshwater soup dough snacks or buy an established dough from a company or individual. I have long suspected that the digestibility of an authentic loaf of soup dough probably depends in part on how the product is prepared. To find out if this was true, the researchers analyzed 500 samples of bread dough, mostly from artisan bakeries on four continents. The researchers immediately realized that location played a minor role in the microbial diversity of the original soup dough. This is one reason why making your own soup dough from scratch can produce very different results in terms of flavor, taste and texture. Nearly a third of the soup cultures tested contained acetic acid bacteria. This result is surprising because previous studies of soup dough have focused almost exclusively on yeast and lactic acid bacteria. While the role of microbial species and their synergistic interactions in shaping the mass properties of acetic acid is important, perhaps the greatest contribution can be made by helping us better understand more complex ecosystems. The average original yeast contains only one yeast species. These include the age of the original yeast, the frequency of feeding, and where it is stored at home. Freshly baked bread at home is an ancient and historically important custom that experienced a cultural revival during the VOCID-19 pandemic pandemic.