Monitoring of killer yeast populations in mixed cultures. Influence of incubation temperature in vinifications simplesMonitoring of killer yeast populations in mixed cultures. Influence of incubation temperature in vinifications simples

MATURANO Y.P.,; NALLY M.C,; TORO M.E.,; CASTELLANOS DE FIGUEROA, LUCÍA INES; VAZQUEZ F.

JOURNAL OF INDUSTRIAL MICROBIOLOGY & BIOTECHNOLOGY

SPRINGER HEIDELBERG

Lugar: New York; Año: 2010 vol. 1 p. 1 - 1

1367-5435

Killer yeasts have been used to combat and prevent contaminating wild-type yeasts which can occur during the production of wine, beer, bread, table olives and as bio-control agents in the preservation of foods. The enological interest in killer yeasts arises because they might dominate a wine fermentation. This work aims at providing a tool to monitor killer and sensitive yeast populations during controlled mixed experiments (microvinifications) taking into account the growth temperature of the samples. Fermentation samples were incubated at two temperatures: 25°C and 37°C (killer toxin inactivation temperature). Colonies developed were transferred to killer phenotype detection medium. In all experiment al conditions samples, significant differences were found in killer yeasts proportion at both incubation temperatures. These results suggest that the biomass of sensitive yeasts is normally underestimated at the standard incubation temperature (25- 30°C), given the fact that the elimination of sensitive cells is common in the proximity to killer yeasts during their development. Incubation of samples at toxin inhibition temperature clearly shows the coexistence of killer and sensitive cells in fermentation systems and, consequently, avoids the underestimation of sensitive yeasts.