Statistical optimization of kojic acid production by a UV-induced mutant strain of Aspergillus terreus

The ability of four Aspergillus strains for biosynthesis of kojic acid was evaluated among which Aspergillus terreus represented the highest level (2.21 g/L) of kojic acid production. Improvement kojic acid production ability of A. terreus by random mutagenesis using different exposure time to ultraviolet light (5–40 min) was then performed to obtain a suitable mutant of kojic acid production (designated as C(5-10), 7.63 g/L). Thereafter, design of experiment protocol was employed to find medium components (glucose, yeast extract, KH(2)PO(4) (NH(4))(2)SO(4), and pH) influences on kojic acid production by the C(5-10) mutant. A 2(5−1) fractional factorial design augmented to central composite design showed that glucose, yeast extract, and KH(2)PO(4) were the most considerable factors within the tested levels (p < 0.05). The optimum medium composition for the kojic acid production by the C(5-10) mutant was found to be glucose, 98.4 g/L; yeast extract, 1.0 g/L; and KH(2)PO(4), 10.3 mM which was theoretically able to produce 120.2 g/L of kojic acid based on the obtained response surface model for medium optimization. Using these medium compositions an experimental maximum Kojic acid production (109.0 ± 10 g/L) was acquired which verified the efficiency of the applied method.