Programme: Applied Biology
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Item FUNGAL-MEDIATED VANILLIC ACID PRODUCTION THROUGH BIOCONVERSION OF GALLIC ACID OBTAINED FROM RICE BRAN(Covenant University Ota, 2025-08) OGUNBAJO, Oluwafemi Omolade; Covenant University DissertationGallic and vanillic acids are naturally occurring phenolic compounds widely used in the pharmaceutical, food, and cosmetic industries due to their antioxidant properties. Rice bran is a nutrient-rich agro-industrial by-product. However, there are challenges of improper disposal and underutilization as a substrate for the production of valuable bioactive compounds. This study investigated the fungal-mediated bioconversion of rice bran into gallic acid under solid-state fermentation (SSF) and its subsequent transformation into vanillic acid through submerged fermentation (SMF) using Aspergillus niger. It was inoculated into a fermentation medium containing pre-treated rice bran and mineral salts and incubated for 5 days at 30 °C. Fermentation was monitored for pH, temperature, UV-Vis absorbance (276nm), and titration. The produced gallic acid was characterized using HPLC, GC-MS, and FTIR. Thereafter, 1% Methanol was introduced into a mineral salt medium containing the produced gallic acid as the substrate, and inoculated 1ml of the inoculum and incubated at 30 °C for 5 days. This was monitored and characterized as in the gallic acid production. During fermentation, the temperature ranged 28-33 °C, pH decreased from 6.5 to 5.2, the absorbance rose from 0.205 to 0.681 nm, and titration increased from 0.016 to 0.075 mol (p<0.05). HPLC quantified 6552.2 mg/L total phenolics, with gallic acid at 2569.8 mg/L. FTIR revealed gallic acid functional groups such as O–H, C=O, and C=C, while GC-MS identified volatile compounds including O-toluic acid, 2(1H)-naphthalene derivatives, and 3H-Cyclodeca[b]furan-2-one. For the vanillic acid production, fermentation filtrate temperature stayed at 29-30 oC, with the pH increasing in acidity from 6.5 to 4.3 through the 5-day period. This corresponded with the results of the titration, showing 0.016 to 0.079 mol results.The GC-MS showed volatile organic compounds present in vanillic acid, including protocatechuic, catechol, and syringic acids. HPLC quantified a total of 15,31203 mg/L of vanillic acid. FTIR revealed vanillic acid functional groups such as OCH₃, OH, and C=O. The results of this study provides strategic insights for sustainable bioprocess approaches in support of SDGs 3 and 12.