Statistical optimization of media components to enhance citric acid production from paddy straw using solid state fermentation

A sequential optimization based on experimental design method was employed to optimize the concentration of media components for improvement of citric acid production from paddy straw by solid state fermentation using Aspergillus niger. The optimization procedure for the media components (NH4NO3, KH2PO4, MgSO4, CuSO4, ZnSO4, FeSO4 and MnSO4) was carried out using the Plaket-Burman Design (PBD) for the screening and Central Composite Design (CCD) for the optimization. The result obtained from (PBD) indicates NH4NO3, KH2PO4 and MgSO4 were the most significant components that affect the citric acid production. The maximum yield obtained by (CCD) was 39.5 g citric acid/kg of paddy straw. The statistical analysis showed that the optimum media concentration was 0.03 g/L for NH4NO3, 2.08 g/L for KH2PO4 and 0.015 g/L for MgSO4, which gives the maximum predicted yield of citric acid (51.1 g citric acid/Kg paddy straw)