EFFECT OF PROTEASE ON THE COFLOCCULATION OF WINE YEASTS

OSCAR ANTONIO SOSA; ESTELA NOEMI SANTILLAN; MARIA CRISTINA MANCA DE NADRA; MARTA ELENA FARÍAS

Tucuman

Congreso; Jornadas de la Asociación de Biología de Tucumán - 2007; 2008

Asociación de Biología de Tucumán

Kloeckera apiculata mc1, express a flocculent phenotype characterized by lectin-galactose interaction, stabilized by Ca2+. The apiculate yeast can coflocculate with non-flocculent strain of Saccharomyces cerevisiae. This work investigates the effect of proteolitic enzymes on the coflocculation between K. apiculata mc1 and S. cerevisiae mc2, with the aim to understand the cell-cell interaction pattern. Pure and mixed culture of both yeast were grown in YMPG medium for 24 h at 28º. The cells were resuspended in PBS plus 1mg.ml-1 protease and incubated for 2 h at 28º C. The flocculation percentage was measured spectrophotometrically and by differential cell counts. The cell surface was examined by SEM. Protease treatment did not cause a modification in the cell viability; however completely abolished selfflocculation and co-flocculation. Co-flocculent yeasts were highly susceptible to chymotrypsin and proteinase K and partially resistant to trypsin. SEM shows a lost of intercellular connecting homogeneous mucus between co-flocculent yeasts, after protease treatment. These results suggest an important role of cell wall proteinic receptor in the coflocculation phenomenon