INFLUENCE OF GLUCOSE ON THE -FLOCCULATION OF Kloeckera apiculata IN CO-CULTURE WITH Saccharomyces cerevisiae

OSCAR ANTONIO SOSA; MARIA CRISTINA MANCA DE NADRA; MARTA ELENA FARIAS

ARGENTINA

Congreso; XI REUNIÓN DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN BIOQUÍMICA Y BIOLOGÍA MOLECULAR (SAIB); 2004

Kloeckera apiculata mc1 isolated from wine posses a flocculent phenotype characterized by protein-carbohydrate interaction, stabilized by Ca2+. We carried out a study of the influence of glucose on the modification of the flocculent phenotype of Kloeckera apiculata in co culture with Saccharomyces cerevisiae. The flocculation degree (DF) was determined by the method of Bonaly and Lematre and glucose by the glucose oxidase method. An increase of DF of pure culture of Kloeckera apiculata was observed in presence of increasing glucose concentrations. The flocculation was inhibited when the apiculate yeast was co-cultured with Saccharomyces cerevisae. In pure cultures of Kloeckera apiculata, the percentages of free cells excluded from the flocs were 92%, 61% and 53% in presence of 20, 50 y 100 g/l glucose, respectively. In mixed cultures, these percentages were higher (95%, 82% and 85%). In co-culture conditions, a higher rate of glucose consumption was observed as consequence of the greater sugar fermentative power of the elliptic yeasts. When the culture media were completely depleted of sugar, the flocculation of Kloeckera apicuata in pure and mixed culture was fully reverted. The results indicate that glucose is an activator of the Kloeckera apiculata mc1 flocculent phenotype. The carbohydrate could lead to different transduction pathways in yeast. In mixed cultures, the greater glucose consumption by Saccharomyces cerevisae, accelerates the flocculation reversion.