The gas released by anaerobic bacteria during fermentation is primarily carbon dioxide. Fermentation is a metabolic process that allows organisms to convert sugars into energy without oxygen. In the case of lactic acid fermentation, which occurs in some bacteria and muscles, lactic acid is produced along with carbon dioxide. In alcoholic fermentation, occurring in yeast, ethanol and carbon dioxide are generated. This process is significant in various industries, including brewing and baking, as it contributes to the production of alcoholic beverages and leavening in bread.