Pilot scale production and application of fungal glucose oxidase-based bio-Fenton oxidation as a pretreatment process for Casuarina equisetifolia biomass to obtain fermentable sugars

This study elaborates on the utilization of Casuarina equisetifolia biomass for the pilot-scale production of glucose oxidase from Aspergillus niger and their subsequent application in the valorization of biomass via bio-Fenton oxidation for fermentable sugar production. Optimized medium parameters (0.13 % of yeast extract, 3.1 % of CaCO3, 0.7 mg of biotin, and 0.06 % of triton X), and operational parameters (120 RPM of agitation, 2 VVM of aeration, 11 % inoculum size, and 80 h of incubation) resulting in 1261±2.08 U/mL of glucose oxidase production in 25 L stirred tank reactor. A potential cost-effective and environmentally friendly method for fermentable sugar production was devised, utilizing C. equisetifolia biomass in conjunction with the bio-Fenton oxidation by glucose oxidase. Through a systematic examination, the optimum process conditions were determined by response surface methodology, including the quantity of hydrogen peroxide and FeSO4 of 25.5:1 ratio, the reaction duration of 13 h, and biomass concentration of 7.5 %. The maximum fermentable sugar concentration optimized was 595±0.62 mg/g of biomass by the bio-Fenton oxidation. These findings illustrate the feasibility of employing bio-Fenton chemistry as an effective pretreatment approach to enhance the accessibility of biomass for fermentable sugar conversion as well as platform chemical production.