HELIA HAJIAN, NAJEEB KAID NASSER AL-SHORGANI, SITI ROZAIMAH SHEIKH ABDULLAH AND WAN MOHTAR WAN YUSOFF
Abstract
The productivity of itaconic acid was studied in submerged culture fermentation employing Aspergillus terreus SUK-1. Several process parameters that includes pH, temperature, ammonium nitrate as the nitrogen source and effect of metal ions were investigated for itaconic acid production in shake flask scale. In this study Response Surface Methodology (RSM) with central composite design (CCD) was employed to optimize the production of itaconic acid by A. terreus SUK-1 based on three variables including pH, temperature (°C) and ammonium nitrate concentration. The effects of these variables on itaconic acid production were analyzed after 7 days fermentation. ANOVA showed that the quadratic model was significant (P<0.0001) and all tested parameters also showed significant effect on itaconic acid production. The estimated optimal parameters for itaconic acid production were pH 2.6, temperature 32oC and ammonium nitrate concentration 1.77 g/L. The effect of CuSO4 (5 to 20 mg/L), ZnSO4 (1 to7 mg/L), FeCl3 (0.5 to 5 mg/L) and CaCl2 (2.5 to 10 g/L) on itaconic acid production resulted in the maximum itaconic acid productivity at10 mg/L CuSO4, 3 mg/L ZnSO4, 2 mg/L FeCl3 and 7.5 g/L CaCl2 under a constant stirring rate of 170 rpm. The optimum productivity of itaconic acid by A. terreus SUK-1 was 223 mg/L.h. The productivity of itaconic acid compare with other research was comparable. The enhancement of itaconic acid concentration produced by A. terreus SUK-1 was successfully optimized by using RSM and non- RSM technique.