SUSTAINABLE PRODUCTION OF BIOETHANOL FROM MAIZE HUSK BY SIMULTANEOUS SACCHARIFICATION AND FERMENTATION USING ACREMONIUM BUTYRI AND ZYMOMONAS MOBILIS

Abstract

A green bio-energy from bio-polymeric resources with the potential in maintaining ecological balance brings about a search for elements and techniques to ease liquid fuel production. Bioethanol was produced using maize husk by simultaneous saccharification and fermentation. Test organisms include fungi and bacteria. The fungi A. butyri was isolated from dead plant matter roots of Piliostigma reticulatum using sabouraud dextrose agar (SDA). The observed cultural and morphological characteristics were identified and compared with those already known and reported fungi taxa. The bacteria used (Acremonium butyri) were obtained from the department of microbiology, Udusok, Nigeria. Proximate compositions of maize husk included protein (6.9%), Ash (5.02%), Moisture (7.6%), Fat (17.0%), Fibre (3.25%), and Carbohydrate (65.52%). The maize husk was pretreated using an H₂SO₄ dilute acid solution. Post-pretreated maize husk, the sample was inoculated with 10⁷ fungal spore cells of A. butyric, incubated at 30°C on a rotary shaker for 72h. The bacteria Z. mobilis 1×10⁸ cells were subsequently inoculated for the next 48h in the same flask. In each duplicate experiment, samples were analyzed for reducing sugar and bioethanol quantity up to 120h. The highest mean of reducing sugar was between 72 (3.865±0.077) and 96h (3.865±0.063). Bioethanol was determined quantitatively using potassium dichromate. About 1% of Standard ethanol concentration was obtained. The diluted 1% was re-diluted with distilled water again and obtained 0, 0.2, 0.4, 0.6, and 0.8. These concentrations added with potassium dichromate reagent were used for the development of a standard ethanol curve using UV-VIS spectrophotometer 588nm. About 2.5ml of sample products was mixed with 1Ml potassium dichromate and absorbance was also taken at 588nm using a spectrophotometer. The quantity of bioethanol in the presence of A. butyri and A. butyri plus Z. mobilis was peak at 72h (0.98%) and 120hrs (1.65%) respectively. A successive increase across the different periods in the quantity of bioethanol was observed. Therefore, A. butyri is a potential agent that can both hydrolyze and ferment sugars. Maize husk is a vital waste with potential sugars that can be used to produce bioethanol.