Melatonin is produced by yeast during alcoholic fermentation

María de los Ángeles Morcillo Parra

Melatonin (MEL) is a neurohormone produced in the pineal gland of humans. Its biological properties are related to the circadian rhythms and antioxidant functions, for example, we use it as an alleviation of subjective feelings of jet lag.  MEL is an ubiquitous molecule which can be synthesized in animals, plants, bacteria and yeasts.

MEL has been also found in wine, a beverage of economic relevance, in which, alcoholic fermentation and yeast role are crucial to MEL production. Some factors as growth phase of yeast and concentration of aromatic amino acids could change the synthesis of this compound.

The purpose of this study was to determine the capacity of different yeasts to produce MEL during alcoholic fermentation. Different Saccharomyces yeast strains (Levucell SC20 y Diamond), used either for industrial fermentations (beer) or as nutritional complements, and non-Saccharomyces yeast strains (Metschnikowia pulcherrima, Starmerella bacillaris) were tested to analyze intracellular and extracellular MEL production in synthetic grape must.

At the beginning of the fermentation, MEL was detected either in Saccharomyces and non-Saccharomyces strains in the intracellular compartment. Production levels differed among strains, being Levucell SC20 and S. bacillaris the microorganisms that presented the highest concentration in each group. By contrast, extracellular MEL was detected at different time-points over the fermentation process, depending on the yeast strain.