Sustainable enhancement of Monascus red pigments using agricultural wastes and biogenic iron nanoparticles

This study systematically optimized the production of red pigments by Monascus ruber through the evaluation of culture media, growth conditions, and sustainable substrate alternatives. Sabouraud Dextrose Broth emerged as the optimal medium, where glucose and peptone were identified as the most effective carbon and nitrogen sources, respectively. Physical parameters, including a pH of 6, 150 rpm agitation, and temperatures of 25–30 °C, were found to support stable pigment production. The application of biologically synthesized iron nanoparticles at 200 ppm significantly enhanced pigment yield (15% increment compared to non-treated samples) by inducing controlled oxidative stress. Agricultural waste valorization was achieved using corn cob hydrolysate (chemically saccharified with 0.15 N HCl) and feather peptone, which replaced 50% of conventional glucose and 100% of peptone without compromising yield. The integration of these optimized conditions resulted in a sustainable and efficient pigment production system, demonstrating the potential of combining waste-derived substrates with nanotechnology for industrial applications.