Integrated production of gluconic acid and xylonic acid using dilute acid pretreated corn stover by two-stage fermentation

Abstract

A sustainable and efficient two-stage fermentation was developed to produce gluconic acid (GA) and xylonic acid (XA) from dilute acid pretreated corn stover (DA-CS) using Gluconobacter oxydans. Cells (6.2 g/L) were obtained after four cycles of fermentation in DA-CS enzyme hydrolysate at 50 ml scale in a shake flask. With each cycle showing complete utilization of glucose with GA productivity rate at 5.3 g/L/h. The enriched cells were then collected and used to ferment DA-CS liquid stream (generated during pretreatment containing mostly xylose) at 50 ml scale in a shake flask to produce XA at a rate of 1.9 g/L/h. Subsequently, the process was scaled up to 1 L. Both GA and XA was produced at the rate of 8.7 g/L/h and 3.7 g/L/h respectively in 36 h. From 1 kg of corn stover we were able to produce 296.2 g GA and 167.4 g XA by two stage fermentation.