Kimchi also uses lactic acid fermentation. Corn ethanol is produced by ethanol fermentation and distillation. Most yeasts used in baking are of the same species common in alcoholic fermentation. Sugars for ethanol fermentation can be obtained from cellulose. Yeast is the microorganism that is responsible for fermentation in beer. Ethanol is produced by microbial fermentation of the sugar. Bacterial fermentation of undigested polysaccharides produces these. This method kills the yeast responsible for fermentation. Haystacks produce internal heat due to bacterial fermentation. "Homolactic fermentation" (producing only lactic acid) is the simplest type of fermentation. It is then milled before soaking again to create the sugars needed for fermentation. Diacetyl arises naturally as a byproduct of fermentation. Diets yielding butyrate and acetate from bacterial fermentation show increased T expression. They achieved this by bottling the wine before the initial fermentation had ended. Polyhydroxyalkanoates are linear polyesters produced in nature by bacterial fermentation of sugar or lipids.