Research Projects

D-allulose, a C-3 epimer of D-fructose, is a bio-safe and palatable sweetener with anti-diabetic, anti-obesity, anti-dyslipidemic, and neuroprotective potential. Its daily intake is comparable to that of caloric sugars like sucrose. D-allulose also improves the texture properties and shelf-life of food products. Chemical synthesis of D-allulose is cumbersome and generates undesirable chemical waste. To address this, biological systems for D-allulose production are needed. Ketose 3-epimerases, such as D-allulose 3-epimerase and D-tagatose 3-epimerase, are bacterial enzymes that catalyze the epimerization of D-fructose to D-allulose. The group demonstrated thermal stability improvement in a D-allulose 3-epimerase by following N-terminal fusion of Smt3 and enzyme immobilization approaches. They also identified a novel D-allulose 3-epimerae gene (daeM) from an extreme temperature thermal spring metagenome. Recently, a novel D-allulose 3-epimerase gene, daeB, was discovered in Bacillus subtilis, exhibiting profuse heat stability at 50°C and a high turnover number. However, translation of this invention is limited by low-level protein expression in heterologous hosts. The proposal aims to construct high-level expression systems with extracellular secretion of enzymes, establish a fermentation approach for enzyme production, immobilize the enzyme to a natural polymer matrix for continuous production of D-allulose, and develop a chemical method for precipitation.