Lactic Acid Fermentation The fermentation method used by animals and certain bacteria, like those in yogurt, is This type of fermentation is used routinely in mammalian red blood cells and in skeletal muscle that has an insufficient oxygen supply to allow aerobic respiration to continue (that is, in muscles used to the point of fatigue). In muscles, lactic acid accumulation must be removed by the blood circulation and the lactate brought to the liver for further metabolism Another familiar fermentation process is alcohol fermentation that produces ethanol, an alcohol (because of this, this kind of fermentation is also sometimes known as ethanol fermentation). There are two main reactions in alcohol fermentation