Influence of oxygen on the biosynthesis of cellular fatty acids,sterols and phospholipids during alcoholic fermentation by Saccharomyces cerevisiae and Torulaspora delbrueckii

Saccharomyces cerevisiae and Torulaspora delbrueckii were grown under different O₂ availabilities on grape must. Oxygen requirements for the two yeasts were different: under anaerobic conditions, S. cerevisiae produced a higher percentage of unsaturated fatty acids, and had a greater cell yield and fermentation activity than T. delbrueckii. Addition of ergosterol (25mg/l) and oleic acid (31mg/l) caused total recovery of cellular growth and the fermentation activity of S. cerevisiae in anaerobiosis, but not of T. delbrueckii. However a short period of aeration to a 48 h culture in anaerobiosis, led to total recovery of the cellular growth and fermentation activity in both yeasts. Likewise, the effect of a short aeration period on unsaturated fatty acid biosynthesis was similar for both species.