The fermentation of cane sugar as substrate by Saccharomyces cerevisiae (enzyme) was critically investigated to obtain certain useful kinetic parameters and to determine the effect of temperature, pH, substrate and yeast (enzyme) concentration on the rate of fermentation. The results indicate that the rate of fermentation (measured as rate of production of CO2) increased in proportion with temperature (optimum 32˚C - 36˚C), pH (optimum
5.5) substrate (optimum 50 v/v%) and yeast concentration (optimum 3.5 - 4.5 w/v%) up to a limit and subsisted either as a plateau and/or, decreases as the case may be. This suggests that the reaction takes place in two steps. The kinetic parameters examined are maximum rate of reaction Vmax (2.0 × 102M∙min−1), catalytic constant, k2 (1.81 × 10−1 min−1), overall rate constant, k (1.53 × 101 min−1), order of initial reaction (approx. first order), dissociation
constant of enzyme-substrate complex, ks (2.74 × 103), Michaelis constant, km (2.74 × 103 M), and the specific activity of enzyme on substrate concentration (1 × 10−1 w/v%). The result of this study showed that the equilibrium step involving k−1/k1 is the limiting step deciding the direction of reaction as well as the specific activity of the enzyme.
Egharevba Felix, Ogbebor Clara, Akpoveta Oshevwiyo Vincent