Which by product of fermentation has been utilized in the production of bread?
Yeasts use sugars in the same way that we do. They convert the sugar to carbon dioxide gas in the fermentation process. If you brew wine or beer at home, you wait until the fermenter stops bubbling
The fermentation process when you prove bread (i.e. let it rise) fills the dough with holes so that the baked bread has a nice spongy texture.