Production of fumaric acid from biodiesel-derived crude glycerol by Rhizopus arrhizus

•R. arrhizus can assimilate crude glycerol and convert it into fumaric acid.•The R. arrhizus pellet can be formed when growing on crude glycerol medium.•The co-fermentation of glycerol and glucose was studied to produce fumaric acid.•By the co-fermentation, the production cost of fumaric acid was reduced by 14%.

This work investigated the capability of Rhizopus arrhizus to assimilate biodiesel-derived crude glycerol and convert it into fumaric acid. After optimizing the initial glycerol concentration, spore inoculum and yeast extract concentration, smaller pellets (0.7 mm) and higher biomass (3.11 g/L) were obtained when R. arrhizus grew on crude glycerol. It was found that crude glycerol was more suitable than glucose for smaller R. arrhizus pellet forming. When 80 g/L crude glycerol was used as carbon source, the fumaric acid production of 4.37 g/L was obtained at 192 h. With a highest concentration of 22.81 g/L achieved in the co-fermentation of crude glycerol (40 g/L) and glucose (40 g/L) at 144 h, the fumaric acid production was enhanced by 553.6%, compared to the fermentation using glycerol (80 g/L) as sole carbon source. Moreover, the production cost of fumaric acid in co-fermentation was reduced by approximately 14% compared to glucose fermentation.

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