Kinetic and physiological parameters in AS-1404 model fitted to experimental data with GA optimization.ParameterControl experimentsTest experimentsMonod constant for cell growth, K3 (g/L)26.1920.08Inhibition constant of cell growth by glucose, Ki (g/L)83.4496.45Inhibition constant of cell growth by ethanol, K3E (g/L)49.9947.61Specific cell death rate, kd (1/h)0.0830.005Maximal specific growth rate, μm (1/h)0.460.985Constant for growth associated ethanol formation, a (g/g)2.892.99Non-growth associated specific ethanol production rate, b (g/g/h)1.991.99Average yield coefficient of cell mass on glucose, YX/G (g/g)0.0020.026Specific rate of substrate consumption for cell maintenance requirements, m (1/h)0.2710.116Full-size tableTable optionsView in workspaceDownload as CSV
Ethanol is a product directly associated with energy generation by microorganism, which essentially means that it is a growth associated product. However, a value of 1.99 g/g/h for constant non-zero value of constant b in Eq. (3) indicates that ethanol formation occurred during stationary phase as well, which is non-growth associated production. The model for fermentation predicts same values of constants a and b for both control and test experiments. Thus, the mode of ethanol production does not get affected by sonication. However, for both control and test experiments, value of constant a was greater than that of b, which suggested that ethanol was predominantly a growth associated product.