Promotion of lactose isomerization to fructose and lactulose in one batch by immobilized enzymes on bacterial cellulose membranes

Abstract

The production of the sugars fructose and lactulose from lactose using the enzymes β-galactosidase and glucose isomerase immobilized on bacterial cellulose (BC) membranes has been investigated. Lactose is hydrolyzed by β-galactosidase at 30 °C to glucose and galactose at a high conversion rate, while at the same temperature, glucose isomerase is not effective in converting the produced glucose to fructose. The rate of the isomerization reaction of glucose to fructose at 70 °C has been studied. Two types of enzyme immobilization were investigated: immobilization in one stage and immobilization in two stages. The results showed that BC membrane increased three-fold the yield and the reaction rate of fructose and lactulose production from lactose. The noteworthy enhancement of BC membranes' impact on the isomerization reaction by immobilized enzymes grants permission for a novel research avenue within the context of white biotechnology development. Additionally, this effect amplifies the role of BC in sustainability and the circular economy.

Keywords: Bacterial cellulose; Circular economy; Dietary fructose; Enzyme immobilization; Glucose isomerase; Lactose; Lactulose; β-Galactosidase.