.The mother plate was allowed to propagate on the potato dextrose agar (PDA) at a constant temperature of 30 ± 2 C in an incubator (Memmert INE 200, Germany). A. niger was then isolated from the mother plate to obtain monospecific colony.
Upscaling in Erlenmeyer flask with 150 mL of potato dextrose broth (PDB) growth medium was carried out for fermentation purpose(Liao et al., 2007). Distilled water was used to prepare the PDB prior to autoclaving at 121 C for 20 min. A. niger was cultivated for 3 days at a constant temperature of 30 ± 2 C in incubator shaker(Lab Companion SI-600, Korea) with a shaking rate of 125 rpm.