Behavior of Kloeckera apiculata flocculent strain in co-culture with Saccharomyces cerevisiae

SOSA O. A.; MANCA DE NADRA, M.C; FARÍAS, M.E.

FOOD TECHNOLOGY AND BIOTECHNOLOGY

Faculty of Food Technology and Biotechnology

Lugar: Zagreb; Año: 2007

1330-9862

We analyzed the behavior of the flocculent Kloeckera apiculata strain in co-culture with the non-flocculent Saccharomyces cerevisiae strain, both yeasts isolated from wine. Pure culture of Kloeckera apiculata (apiculate yeast) exhibits 75 % flocculation in YPG medium after 24 h incubation at 28 °C. This yeast expresses a weak flocculent phenotype in glucose-poor medium (10 % of flocculated cells). The addition of increasing glucose concentrations to this medium induces yeast flocculation. When the apiculate yeast was co-inoculated with a non-flocculent strain of Saccharomyces cerevisiae (elliptic yeast), an increase of the elliptic cells number that settled at the bottom of the culture was observed. Electron microscopy observations of the aggregates formed in the mixed culture confirmed that apiculate and elliptic yeasts can interact and establish a binding between them through homogeneous mucus. However, a lower percentage of Kloeckera apiculata flocculation with respect to the pure cultures was observed, this behavior being correlated with a higher rate of glucose consumption by Saccharomyces cerevisiae. The prompt coflocculation of Kloeckera apiculata with Saccharomyces strains and the induction of this phenomenon by glucose could be considered an important biotechnological tool for the early decreasing of indigenous saccharomycetic flora from the media, before the inoculation of a selected starter strain to carry out more controlled alcohol fermentation