Production of D-Allose From D-Allulose Using Commercial Immobilized Glucose Isomerase

Rare sugars are regarded as functional biological materials due to their potential applications as low-calorie sweeteners, antioxidants, nucleoside analogs, and immunosuppressants. D-Allose is a rare sugar that has attracted substantial attention in recent years, owing to its pharmaceutical activities, but it is still not widely available. To address this limitation, we continuously produced D-allose from D-allulose using a packed bed reactor with commercial glucose isomerase (Sweetzyme IT). The optimal conditions for D-allose production were determined to be pH 8.0 and 60°C, with 500 g/L D-allulose as a substrate at a dilution rate of 0.24/h. Using these optimum conditions, the commercial glucose isomerase produced an average of 150 g/L D-allose over 20 days, with a productivity of 36 g/L/h and a conversion yield of 30%. This is the first report of the successful continuous production of D-allose from D-allulose by commercial glucose isomerase using a packed bed reactor, which can potentially provide a continuous production system for industrial applications of D-allose.

From a Sequential Chemo-Enzymatic Approach to a Continuous Process for HMF Production from Glucose

Notably available from the cellulose contained in lignocellulosic biomass, glucose is a highly attractive substrate for eco-efficient processes towards high-value chemicals. A recent strategy for biomass valorization consists on combining biocatalysis and chemocatalysis to realise the so-called chemo-enzymatic or hybrid catalysis. Optimisation of the glucose conversion to 5-hydroxymethylfurfural (HMF) is the object of many research efforts. HMF can be produced by chemo-catalyzed fructose dehydration, while fructose can be selectively obtained from enzymatic glucose isomerization. Despite recent advances in HMF production, a fully integrated efficient process remains to be demonstrated. Our innovative approach consists on a continuous process involving enzymatic glucose isomerization, selective arylboronic-acid mediated fructose complexation/transportation, and chemical fructose dehydration to HMF. We designed a novel reactor based on two aqueous phases dynamically connected via an organic liquid membrane, which enabled substantial enhancement of glucose conversion (70%) while avoiding intermediate separation steps. Furthermore, in the as-combined steps, the use of an immobilized glucose isomerase and an acidic resin facilitates catalyst recycling.

Comparison Study of Experimental and Simulation in the Glucose Isomerisation Process in a Fixed-Bed Reactor

Production of fructose from glucose isomerisation process using commercial immobilized glucose isomerase (IGI) was conducted in a fixed-bed bioreactor. A semi-empirical kinetic model based on the mechanism of the glucose isomerisation process has been proposed. The values of maximum rate of reaction, Vm ,g L-1 min-1 are (1.82, 1.86, 1.93 and 0.37), for Michaelis-Menten constant Km, g L-1 the values are (1.04, 1.11, 1.24 and 0.35). In this modified model, known as MM3 the variation of temperature, pH, and initial substrate concentration, feed flow rates have been taken into account. The validation of the models with experimental data was checked in terms of AAE and R2. The values of correlation coefficient, R2 (> 0.95) indicated that MM3 model was well fitted to the experimental data.