FLOCCULATION OF Kloeckera apiculata mc1. MODIFICATION BY NUTRITIONAL VARIATIONS.

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

ARGENTINA

Congreso; Jornadas Cientificas de la Asociacion de biología de Tucuman - 2002; 2003

Floccultation is a process characterized by reversible and spontaneous aggregation of yeast cells forming clumps that easily separate from the medium. Tthis work investigates the variations in flocculation by modifying the nutritional conditions of the culture medium YMPG, Sabouraud and grape juice media are used. The flocculation degree (DF) was determined by the method of Bonaly and Lematre, and cell surface hydrophobicity by the microbial adhesion to hydrocarbons (MATH). The DF in YMPG, Sabouraud and grape juice media were 4,3 and 1, respectively. There were not marked differences in hydrophobicity in the assayed media. To investigate the effect of medium componentson the flocculation, yeasts were deflocculated and resuspende in the YMPG medium and in its individual components. Yeast flocculated again en the YMPG medium (DF=4) and the Ca2+ addition (2 or 10 mM) increased the fenomenon (DF=5); cells treated with 20 g/l peptone aggregated with a DF=4 and at concentrations of 5 and 2 g/l the DF decreased to 4 and 3, respectively. Similar results were obtained when the cells were treated with malt extract. Different yeast extract concentrations did not affect DF. In conclusion, the flocculation was more effective in rich media. The Kloeckera apiculata mc1 phenotype would be similar to NewFlo of Saccharomyces cerevisiae phenotype.