homofermentation

Homofermentation is a form of lactic acid fermentation in which most of a carbohydrate substrate is converted to lactic acid. It is carried out by homofermentative lactic acid bacteria, which metabolize sugars primarily through glycolysis to pyruvate and then reduce pyruvate to lactate via lactate dehydrogenase. The overall reaction of glucose metabolism in this pathway yields two molecules of lactic acid per glucose, with about two ATP generated per glucose and NAD+ regenerated, while producing little to no CO2 or other end products. The process results in rapid acidification of the substrate and is used in food preservation and dairy fermentation, among other applications.

In contrast, heterofermentation produces lactic acid along with other products such as ethanol or acetic acid and carbon dioxide, via the phosphoketolase pathway, and typically yields less ATP per glucose. The distinction between homo- and heterofermentative lactic acid bacteria helps explain differences in flavor, texture, and gas production in fermented foods.

Homofermentative LAB are used in dairy fermentation to rapidly acidify milk, aiding in the production of certain cheeses and other dairy products. They also contribute to the acidification of various fermented vegetables and soy products and are studied for silage fermentation and industrial production of lactic acid. Factors such as temperature, pH, and available sugars influence pathway activity and product profiles.