Killer activity of Saccharomyces cerevisiae strains: partial characterization and strategies to improve the biocontrol efficacy in winemaking

LUCÍA M. MENDOZA; RAÚL R. RAYA; MIGUEL FERNÁNDEZ DE ULLIVARRI

ANTON LEEUW INT. J. G.

SPRINGER

Lugar: Berlin; Año: 2014 vol. 106 p. 865 - 878

0003-6072

Killer yeasts are considered potential biocontrol agents to avoid or reduce wine spoilage by undesirable species. In this study two Saccharomyces cerevisiae (Cf8 and M12) strains producing killer toxin were partially characterized and new strategies to improve their activity in winemaking were evaluated. Killer toxins were characterized by biochemical tests and growth inhibition of sensitive yeasts. Also genes encoding killer toxin were detected in chromosome of both strains by PCR. Both toxins showed optimal activity and production at conditions used during the wine-making process (pH 3.5 and temperatures of 15-25 °C). In addition, production of both toxins was higher when a nitrogen source was added. To improve killer activity different strategies of inoculation were studied, being the sequential inoculation of killer strains the best combination to control the growth of undesired yeasts. Sequential inoculation of Cf8-M12 showed a 45 % increase of killer activity on sensitive S.cerevisiae and spoilage yeasts. In presence of ethanol (5-12%) and SO2 (50 mg/L) the killer activity of both toxins was increased, especially for toxin Cf8. Characteristics of both killer strains support their future application as starter cultures and biocontrol agents to produce wines of controlled quality.