Michaelis-Menten-Aiba Kinetics of Batch Ethanol Fermentation using Saccharomyces cerevisiae HBY3 Strain

Author : Azucena, Eric John Flores
Major Adviser : Edwin S. Tapang
Committee Members : Acda, Reynaldo I.; Manoto, Russel D.
Year : 1994
Month : April
Type : Thesis
Degree: BS
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The effect of different sugar concentrations on the kinetic parameters of the Michaelis-Menten and Aiba Model Equations using Saccharomyces cerevisiae HBY3 in a batch fermentation was determined.

Five batch fermentations at different initial sugar concentrations were studied, namely 5 g/L, 10 g/L, 40 g/L, 100 g/L and 150 g/L. The operating conditions were at room temperature, with an agitation speed of 250 rpm and an aeration of 1 vvm.

The maximum specific growth rate, µm, maximum production rate, vm, ethanol inhibition constant for growth and production rate, K1 and K2, and the yield factor for product on substrate, Yp/s, of the fermentation models proposed by Aiba (1968) were determined. Results showed that µm and vm increased as the initial sugar was increased. The ethanol inhibition constants, K1 and K­2, as well as the yield factor Yp/s, decreased at increased initial sugar due to inhibition.

The values calculated were; for µm (h-1) : 0.37 0.28, 0.31, 0.36 and 1.06; for vm (h-1): 1.10, 0.79, 1.32, 1.09 and 2.05; for K1 (g/L): 0.10, 0.053, 0.071, 0.06 and 0.054; for K2 (g/L): 0.06, 0.059, 0.045, 0.03 and 0.039; for Yp/s (g EtOH/g Sugar) : 0.50, 0.48, 0.46, 0.41 and 0.37; for batch fermentations at 5 g/L, 10 g/L, 40 g/L, 100 g/L and 150 g/L initial sugar concentrations, respectively.

It was also found out that there was shift from near linear to an exponential form of ethanol inhibition in both biomass and product formation rates. A computer software ETHANOL v1.0 was developed and used for the graphical differentiation of the rates of growth, product formation and substrate consumption for the determination of the kinetic parameters.

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