Influence of oxygen transfer and uptake rates on xylonic acid production from xylose by Gluconobacter oxydans

Abstract In this work, the influence of oxygen transfer and uptake rates on xylonic acid production from xylose by Gluconobacter oxydans in a stirred tank bioreactor is studied. The effect of oxygen transfer coefficient is experimentally evaluated under different cell concentrations, agitation and aeration rates. Under non-oxygen limitation conditions, the maximum specific oxygen uptake rate and xylonic acid production rate, respectively, are about 18.0 mmolO2/gx/h and 6.0 g/gx/h. For a cell concentration of 1 and 1.5 g/L, respectively, a minimum kla value of 105.5 and 134.2 h-1 is found to prevent the oxygen transfer limitation and guarantee the highest cell activity. These results will assist in determining optimal hydrodynamic operating conditions for maximizing xylonic acid production, and encourage future utilization of C5 sugars from lignocellulosic biomass.