Physicochemical parameters optimization and peroxidase characterization from Aspergillus niger native strain by solid-state fermentation for improved dye decolorization

The hyper yield of peroxidase (POX) was investigated for a novel native Aspergillus niger strain identified by 18S RNA analysis. A. strains sequences were submitted to GenBank; IDs allotted MN611114.1 (BMB 17) and MN559756.1 (BMB-18). in combination showed enhanced activity (601.5 U/mL) solid-state fermentation comparison their individual activities. POX purified ammonium sulfate, size exclusion gel chromatography exhibited 7.83-fold increase concentration (13.3 U/mg) BMB17 BMB 18 (11.8 & 7.6 U/mg respectively). best obtained with pH 6.5, 37 °C, 5 days incubation. Using guaiacol as substrate, maximum (Vmax) 537 U/mL corresponding Michaelis constant (Km) value 126 µM. Calcium chloride worked activator at 300 400 mM. Zinc sulfate (500 mM), EDTA (5 mM); ethanol, propanol, acetonitrile (50%) inhibited (18-30%) POX. Urea (1M), copper mM) strongly up 40%. Polysorbate-80 (1%) slightly reduced the 10% 15%. BMB17+18-induced promising dye decolorization (88-98%) against all vat dyes, methylene blue, phenol red.