Kinetic study and mathematical modelling of glucose dehydrogenase-catalysed glucose oxidation in a batch reactor and in a continuously operated microreactor

The growing gap between global energy demand and the limits of conventional energy sources such as fossil fuels underline the need for alternative solutions. Hydrogen, known for its high energy yield, is a promising candidate among future energy sources. Biohydrogen, i.e. hydrogen produced from biological sources, is a particularly interesting option for renewable energy. One method for biohydrogen production is the enzymatic conversion of glucose into gluconic acid, accompanied by the regeneration of the coenzyme with the second enzyme, hydrogenase, and the simultaneous production of molecular hydrogen. In this study, the reaction of glucose oxidation catalysed by the glucose dehydrogenase (GDH) from Pseudomonas spp. with the coenzyme NAD⁺ was investigated both in a batch reactor (V = 100 mL) and in a continuously operated microreactor (V = 4 µL). In order to understand the mechanism of the reaction, a kinetic characterization of GDH was performed in batch experiments. With the data obtained, the kinetics of glucose oxidation were described by a two-substrate Michaelis–Menten model that takes into account substrate inhibition and competitive product inhibition. The mathematical models of glucose oxidation in both batch and microreactor systems were proposed and validated by independent experiments. The results showed that the reaction performed in a microreactor is two orders of magnitude faster than in a batch reactor. This emphasises the significant potential of microreactors to increase the efficiency of glucose biotransformation by using GDH and consequently the biohydrogen production.