Production of Fructooligosaccharides Using a Commercial Heterologously Expressed Aspergillus sp. Fructosyltransferase

The catalytic properties of Seqenzym((R)) FT, a fungal fructosyltransferase heterologously expressed in yeasts, were investigated at a temperature of 55 degrees C and pH 5.5. The initial rate measurements showed that the transfructosylation rate was only slightly inhibited by sucrose above the concentration of 1.5 M. A rather low level of hydrolytic side activity was observed even at sucrose concentrations as low as 0.25 M. In progress curve experiments, the mass yield of fructooligosaccharides (FOS) reached a maximum value of 57% at this sucrose concentration, although it dropped to about 35% later on. At high initial sucrose concentrations up to 2 M, the FOS yield reached a maximum value of approximately 63% at a sucrose conversion of approximately 90%. Although neither the yield nor the conversion changed much later on, the progress of the reaction was manifested by the gradual depletion of shorter chain FOS, 1-kestose and nystose, and the accumulation of 1-beta-fructofuranosyl nystose. At initial sucrose concentrations of 2 M, the degree of polymerization expressed through the number of fructosyl units grew from 2.3 at a conversion degree of 87% to 3.1 at a conversion degree of 94%. Compared to other commercial preparations, Seqenzym((R)) FT can better produce FOS with a higher degree of polymerization.

Automated summary

The catalytic properties of Seqenzym((R)) FT, a fungal fructosyltransferase heterologously expressed in yeasts, were investigated. The study found that the transfructosylation rate was slightly inhibited by sucrose concentrations above 1.5 M, while hydrolytic side activity was low even at sucrose concentrations as low as 0.25 M. The progress of the reaction was characterized by the depletion of shorter chain FOS and the accumulation of 1-beta-fructofuranosyl nystose, indicating Seqenzym((R)) FT's ability to produce FOS with a higher degree of polymerization compared to other commercial preparations.