Investigation on macrokinetics of heterogeneous process of monosaccharide isomerization using non-growing cells of a glucoisomerase producer Arthrobacter nicotianae immobilized inside SiO2-xerogel

Abstract

Macrokinetic peculiarites of heterogeneous process of monosaccharide (glucose/fructose) isomerization using biocatalysts prepared by incorporation of non-growing cells of a glucose isomerase-producing strain Arthobacter nicotianae inside SiO2-xerogel have been investigated. It was shown that the process proceeds in kinetic regime without diffusion limitation and biocatalyst activities at 60 and 75°C were 19 and 32 U/g, respectively. Time of equilibrium in the reaction of monosaccharide isomerization was a function of starting (“triggering”) glucose isomerase activity in a unit of reaction volume. When the activity exceeds 10 U/ml, equilibrium equimolar mixture of glucose and fructose was produced within a few hours. It was established that a continuous process carried out in a plug-flow packed-bed reactor is more efficient than a batch process accompanied with recycling, first of all, to significant improvement of operation stability of the designed biocatalysts. Under model conditions of industrial heterogeneous process of producing glucose-fructose syrups, the half-life time of inactivation of the biocatalysts was more than 500 h at (65 ± 5)°C.