Corn cob and plantain peel extracts as sustainable growth substrates for filamentous fungal cultivation

Abstract:

Approximately 78 million tonnes of corn cob and 42 million tonnes of plantain peel residues are generated annually across sub-Saharan Africa, representing a largely untapped reservoir of nutrients suitable for microbiological applications. This research evaluated the efficacy of corn cob extract, plantain peel extract, and their combination as alternative growth substrates for the cultivation of four filamentous fungal species: Aspergillus niger, Aspergillus flavus, Trichoderma harzianum, and Penicillium chrysogenum. The agricultural waste substrates were collected from processing centers in the Greater Accra Region, Ghana, and processed through sequential extraction involving hot water treatment, enzymatic hydrolysis, and filtration to obtain nutrient-rich liquid media. These liquid extracts were supplemented with bacteriological agar to prepare solid media formulations. The combined corn cob-plantain peel medium demonstrated the highest overall fungal biomass production, reaching 13.2 g/L for A. niger after 14 days of incubation at 28°C, compared to 10.8 g/L on potato dextrose agar control. Enzyme activity assays revealed significantly enhanced cellulase (52.4 U/mL) and amylase (48.9 U/mL) production on the combined medium relative to individual waste media and the commercial control. The pH monitoring throughout the cultivation period showed progressive acidification across all media types, with the combined medium reaching a final pH of 3.6, consistent with organic acid production during active fungal metabolism. Statistical analysis confirmed significant differences in biomass yield and enzyme activity among media formulations (p<0.05). The combined corn cob-plantain peel medium was identified as a promising, cost-effective alternative to commercial fungal cultivation media, offering simultaneous benefits of waste valorization and enhanced enzyme production for industrial applications.