Influence of pH and Initial Glucose Concentration on the Growth of Saccharomyces cerevisiae Yeast Strain by Gravitational Field Flow Fractionation

Abstract

Gravitational field-flow fractionation (GrFFF) was applied for the study of the growth of Saccharomyces cerevisiae yeast strain, in the presence or the absence of corn and wheat starch granules as immobilization carriers. Fermentations were conducted at different values of pH (3.0, 4.0, 5.0, and 6.0) and initial glucose concentration (177 g/L, 205 g/L, 247 g/L and 300 g/L) in order to find the most favorable situation for the growth and proliferation of Saccharomyces cerevisiae cells. The distinction of the phases of the yeast cell cycle was also succeeded by the same technique. The results indicate that the growth of yeast cells was enhanced at pH 5.0 and glucose concentrations of 177 g/L and 205 g/L. Higher glucose concentrations (247 g/L and 300 g/L) acted as an inhibitor to cell proliferation. Immobilization on wheat starch provided wider peak profiles, suggesting a broad size of cells and lower concentrations of haploid cells comparing to cells immobilized on corn starch granules. The determination of Michaelis-Menten constants for free and immobilized cells proved the higher affinity of immobilized cells towards the substrate. The values found were in good agreement with those reported in literature.

Keywords:

• corn and wheat starch granules
• gravitational field-flow fractionation
• immobilization carrier
• Saccharomyces cerevisiae
• yeast growth

ACKNOWLEDGEMENTS

This article is part of the 03ED657 research project, implemented within the framework of the “Reinforcement Programme of Human Research Manpower” (PENED) and co-financed by National and Community Funds (20% from the Greek Ministry of Development-General Secretariat of Research and Technology and 80% from E.U.-European Social Fund).