Applied Biochemistry and Biotechnology, Vol.187, No.2, 449-460, 2019
Factors Affecting Production of Itaconic Acid from Mixed Sugars by Aspergillus terreus
Itaconic acid (IA; a building block platform chemical) is currently produced industrially from glucose by fermentation with Aspergillus terreus. In order to expand the use of IA, its production cost must be lowered. Lignocellulosic biomass has the potential to serve as low-cost source of sugars for IA production. It was found that the fungus cannot produce IA from dilute acid pretreated and enzymatically saccharified wheat straw hydrolysate even at 100-fold dilution. The effects of typical compounds (acetic acid, furfural, HMF and Mn2+, enzymes, CaSO4), culture conditions (initial pH, temperature, aeration), and medium components (KH2PO4, NH4NO3, CaCl(2)2H(2)O, FeCl(3)6H(2)O) on growth and IA production by A. terreus NRRL 1972 using mixed sugar substrate containing glucose, xylose, and arabinose (4:3:1, 80gL(-1)) mimicking the wheat straw hydrolysate were investigated. Acetic acid, furfural, Mn2+, and enzymes were strong inhibitors to both growth and IA production from mixed sugars. Optimum culture conditions (pH 3.1, 33 degrees C, 200rpm) and medium components (0.8g KH2PO4, 3g NH4NO3, 2.0g CaCl(2)2H(2)O, 0.83-3.33mg FeCl(3)6H(2)O per L) as well as tolerable levels of inhibitors (0.4g acetic acid, <0.1g furfural, 100mg HMF, <5.0ppb Mn2+, 24mg CaSO4 per L) for mixed sugar utilization were established. The results will be highly useful for developing a bioprocess technology for IA production from lignocellulosic feedstocks.
Keywords:Itaconic acid;Aspergillus terreus;Submerged fermentation;Mixed sugars;Inhibitory compounds;Mn2+