Development of a hollow-fiber membrane bioreactor system for the continuous production of 2,5-diketo-D-gluconic acid

A hollow-fiber membrane bioreactor system for the continuous production of 2,5-diketo-gluconic acid (2,5-DKG) was constructed and demonstrated. Additionally, key control parameters affecting the production of 2,5-DKG were identified. Pantoea citrea, which possesses three membrane bound enzymes that convert D-glucose into 2,5-DKG, was contained within the extracapillary space of the reactor. The system was designed to provide direct oxygenation to the biomass in the reactor, while liquid nutrients were provided through the intracapillary space. Experiments in which biomass concentration within the reactor and substrate throughput rate were varied identified key operating parameters that control product titre and the volumetric production rate of the system Under the operating conditions used in the experiments, 2,5-DKG concentrations as high as 13 g/L were observed and maintained for 37 hours. Yields as high as 0.54 g 2,5-DKG/g glucose consumed were seen and a maximum volumetric productivity (based upon intracapillary volume) of 3.9 g/L/hr was achieved.