Thermal Stability of fructosyltransferase from Aureobasidium pullulans

The thermal stability of a biocatalyst in the form of whole cells of the fu ngi Aureobasidium pullulans exhibiting fructosyltransferase activity was in vestigated during a batch catalytic process of fructooligosaccharide produc tion. The stability of fructosyltransferase was monitored during 8 h with r espect to temperature and overall saccharide concentration. A fructosyltran sferase activity assay was developed for the monitoring of enzyme activity that was based on the rate of formation of 1-kestose measured by an HPLC me thod. It was found that the biocatalyst inactivated rather quickly at tempe ratures above 60 degreesC even at high saccharide concentrations. The stabi lizing effect of saccharide concentration on the fructosyltransferase activ ity was investigated at 55 degreesC. A kinetic equation of enzyme inactivat ion, based on a reversible one-step reaction and simple exponential relatio nships of the rate constants and on the overall saccharide concentration, w as suggested and statistically verified.