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The kinetic parameters of both glucose isomerization to fructose and immobilized glucose isomerase (GI) inactivation calculated under different conditions are compared and discussed. Utilizing these figures, the possibility of generalizing a linear model, previously proposed for the kinetics of glucose isomerization by immobilized glucose isomerase, is investigated, so as to apply them to whole ranges of temperature and concentrations of actual interest in industrial processes. The proposed model is a satisfactory approximation of the more involved Briggs–Haldane approach and substantially simplifies the problem of optimizing an industrial fixed‐bed column for high‐fructose corn syrup (HFCS) production. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 63: 273–284, 1999.

The reactivity and thermostability of a novel mycelium-bound carboxylesterase from lyophilized cells of Aspergillus oryzae are explored in organic solvent. Ethanol acetylation was selected as reference esterification reaction. High carboxylesterase activity cells were used as biocatalyst in batch esterification tests at 12.5 < S(o) < 125 mmol L(-1), 5.0 < X(o) < 30 g L(-1), 0.49 < log P < 4.5 and 30 < T < 80 degrees C, as well as in residual activity tests after incubation at 40 < T < 90 degrees C. The starting rates of product formation were used to estimate with the Arrhenius model the apparent activation enthalpies of the enzymatic reaction (29-33 kJ mol(-1)), the reversible unfolding (56-63 kJ mol(-1)), and the irreversible denaturation (22 kJ mol(-1)) of the biocatalyst.

Hydrogen bioproduction from agro-industrial residues by Enterobacter aerogenes in a continuous packed column has been investigated and a complete reactor characterization is presented. Experimental runs carried out at different residence time, liable of interest for industrial application, showed hydrogen yields ranging from 1.36 to 3.02 mmol H 2 mmol À1 glucose or, in other words, from 37.5% to 75% of the theoretical hydrogen yield. A simple kinetic model of cell growth, validated by experimental results and allowing the prediction of biomass concentration pro®le along the reactor and the optimization of super®cial velocity, is suggested. By applying the developed approach to the selected operative conditions, the identi®cation of the optimum super®cial velocity v 0,opt of about 2.2 cm h )1 corresponding to the maximum hydrogen evolution rate H 2gYmax , was performed.