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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.

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.

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.

An attempt is presented and discussed to adapt a well-known process successfully employed in the U.S.A. for the simultaneous treatment of the organic fraction of municipal solid waste (MSWOF) and sewage sludge to the particular situation of water works in Italy

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One of the best and cleanest systems to produce electric energy is represented by fuel cells, whose natural fuel is hydrogen. In this paper, the production of hydrogen rich biogas is studied. This process contributes to create a system for biomass recovery, which eliminates organic pollutants and produces energy with high ef®ciency without atmospheric emissions. The study has been based on Escherichia coli and Enterobacter aerogenes strains. The research deals with batch reactors and veri®cation of optimal conditions of hydrogen production. The realization of the optimal working conditions would conduce to the realization of a reactor suitable to feed a stack of the above mentioned fuel cells. In view of industrial applications, some different ways have been considered to greatly enhance the process performance, in terms of rate of hydrogen production, ef®ciency of hydrogen utilization and/ or biosynthesis of valuable subproducts.List of symbols C glucose concentration at the end of the fermentation (g l A1 ) C 0 initial glucose concentration (g l A1 ) n hydrogen evolution (mmol) n max maximum hydrogen evolutiion (mmol) r max maximum rate of hydrogen evolution (mmol l A1 h A1 ) r max maximum speci®c rate of hydrogen evolution (mmol h A1 g A1 cells ) Y max maximum yield (mmol H 2 mmol A1 glucose ) IntroductionFuel cells can be considered to be one of the cleanest and most ef®cient systems to convert the chemical energy stored in several categories of substances, owing to their high conversion ef®ciency and environmental compatibility. Among these substances hydrogen plays a pre-eminent role, thanks to its good reactivity and high oxidation energy [1]. Moreover, hydrogen is an attractive energy source for replacing conventional fossil fuels, both from the economic and environmental standpoints [2]. In general, there are two ways to produce hydrogen with living organisms: one is hydrogen production by photosynthetic organisms and the other is fermentative hydrogen production. Several facultative and strictly anaerobic bacteria were used in the fermentation of different substrates [3±5].The main advantages of the fermentative hydrogen production may be summed up as follows [6]:± production for 24 hours a day without light; ± use of photosynthetic products as substrates; ± use of industrial and/or agricultural wastes as substrates; ± metabolites, except hydrogen, can also be used.Moreover, as the rate of fermentative hydrogen production rate is usually higher than the photohydrogen evolution one, hydrogen bio-production via fermentation appears most likely the technique to be adopted in view of industrial application. Fermentation of high BOD wastes or by-products seems to be a very promising way for producing hydrogen to be used in fuel cells, as it simultaneously allows a good recovery of energy and some valuable by-products, satisfying the need of environmental protection. To this purpose, research on economical feasibility of a continuous bioprocess suitable to feed phosphoric acid fuel cell (PAFC) has been undert...