Stepped utilization of xylose and glucose in fermentation of fumaric acid by Rhizopus arrhizus

The fumaric acid production by Rhizopus arrhizus using xylose as the carbon source of seed culture medium and glucose as carbon source of fermentation medium was studied. In the seed culture, the biomass of Rhizopus arrhizus obtained using xylose was more than that using glucose. The conditions of the seed culture were optimized. The results showed that the optimal xylose concentration was 30 g/L, the suitable spore concentration range (4-6) × 10⁵ mL^-1 and the seed age range 32-40 h. The final concentration of fumaric acid was 53.51 g/L in the fermentation medium containing 100 g/L glucose. The result implies that the problem of low conversion rate of xylose could be avoided, and the availability of xylose improved, which would facilitate further study on the stepped utilization of lignocellulose hydrolysate in fermentation of fumaric acid.