Potentials of Acremonium butyri fungus in pre-treatment and hydrolysis using Rice husk substrate for biofuel production: A short communication

Abstract

There is increasing interest in the area of biofuel production due to concerns about fossil fuel depletion from over-exploitation and crises. During biofuel production, the substrate needs to undergo pre-treatment and hydrolysis, where acids and alkalis are typically used. In this study, Acremonium butyri was employed for both pre-treatment and hydrolysis. The structural compositions of rice husk were determined, with extractives, hemicellulose, and lignin content assessed via Soxhlet extraction, while cellulose was determined as the difference from the extractives, hemicelluloses, and lignin. Acremonium butyri was isolated from dried roots of Piliostigma reticulatum (Kalgo) by placing the roots in a clean plastic container in a moist environment for 7 days, after which fungal growth appeared. The growth was aseptically transferred to prepared SDA plates and kept at room temperature. The fungal growth was identified based on its physical and microscopic characteristics. Approximately 50g of rice husk was mixed with 500ml of distilled water in a 1:10 ratio to obtain a homogeneous slurry, then inoculated with 2ml of the prepared Acremonium butyri solution and incubated at room temperature for 3 weeks, with frequent shaking at specified intervals. A reducing sugar test was conducted to determine the reducing sugar released, using a UV-VIS spectrophotometer. The results showed that rice husk contained 32%, 30%, 29%, and 8.4% of cellulose, hemicelluloses, extractives, and lignin, respectively. A total of 0.936g/l of reducing sugar was released after 3 weeks of pre-treatment. The results suggest that Acremonium butyri successfully separated the components of rice husk (pre-treatment) and broke down cellulose and hemicelluloses into their monomers (hydrolysis), releasing sugar. Thus, Acremonium butyri is a promising microorganism for biological pre-treatment and hydrolysis in biofuel production.