Lactic acid fermentation is a metabolic process that occurs in some bacteria and animal cells in the absence of oxygen. It consists in the converting of a glucose molecule (or other fermentable sugar) into two molecules of pyruvic acid which are then reduced to lactic acid. This metabolic process takes its name from the main final product but is also known as homolactic fermentation, in order to distinguish it from Heterolactic fermentation which has a different mechanism.
Lactic acid fermentation is found principally in Lactobacillus and in anaerobic metabolism of some tissue (muscle) of multicellular organisms. It can be found in the vagina and in the human gastrointestinal tract, where it plays such an important role that some consider lactobacillus as probiotics.
Lactic acid fermentation can cause tooth decay and is used in the preparation of numerous foods including yogurt, kefir, capers and sauerkraut.