Biosynthesis of Oligodextrans Through Synergistic Catalysis of Dextransucrase and Dextranase in a Recycle Membrane Bioreactor

A continuous synthesis process for the production of oligodextrans from sucrose by using dextransucrase and dextranase in a recycle ultrafiltration membrane bioreactor was developed. During continuous oligodextrans synthesis, changes in weight-average molecular weight (Mw) and polydispersity index ( D value) in the second feed tank (i) were monitored by high-performance gel permeation chromatography. Mw decreased with increasing reaction time, resulting in an increasingly homologous solution of low Mw oligodextrans (approximately 1 × 10 4 Da). The D value of the oligodextrans produced was nearly 1.0. In addition, the polymer degradation model well described the kinetics of Mw changes in oligodextrans. Results showed that recycle membrane bioreactor coupled with dextransucrase and dextranase is a simple and effective method that can be used to produce and improve the quality of oligodextrans.