Glucose production from maltodextrins employing a thermophilic immobilized cell biocatalyst in a packed-bed reactor

This research is focused on the development of an immobilized cell biocatalyst applicable for the conversion of maltodextrins into glucose at high temperatures. In particular, Escherichia coli BL21 (DE3) cells expressing α-glucosidase from Sulfolobus solfataricus MT4 were entrapped in a Ca-alginate polysaccharidic matrix obtaining over 70% immobilization yield. Compared to the free α-glucosidase, the immobilized cells showed a shift of optimal pH towards alkaline (from 5.0 to 5.5) and the same increasing activity up to 100 °C. These biocatalyst beads were packed into a tubular reactor, which was exploited for the biotransformation of a commercial dextrin mixture at industrial concentrations (30–40%, w/v) into glucose at 75 °C, achieving up to 98% conversion. The corresponding glucose productivity was about 1.75 g h−1 gbiocatalyst−1.