Sometimes even when oxygen is present and aerobic metabolism is happening in the mitochondria, if pyruvate is building up faster than it can be metabolized, the fermentation will happen anyway.
Ponekad čak i kad je kiseonik prisutan i aerobni metabolizam se odvija u mitohondrijama, ako se piruvat nakuplja brže nego što može da bude metabolizovan, fermentacija će se odvijati.