Abstract

---

The identity, diversity and dynamics of bacterial and fungal communities involved in the production of bioethanol from corn waste (corn cob) were studied. Corn cob was pretreated and hydrolyzed using concentrated H2SO4 then, neutralized with NaOH to pH6.5. The corn waste was introduced as source of indigenous organisms and fermentation was done for 7days. The fermented broth was distilled and ethanol yield was measured with a volumetric flask. Microbial succession was examined using standard microbiological procedures and the isolates were identified by molecular identification techniques. The physicochemical analysis such as pH, total suspended solids, total dissolved solids and total reducing sugars were tested during fermentation. Ethanol optimum yield was 10.00g/l and total quantity was 45.00g/l. The indigenous bacteria isolated and identified were Klebsiella pneumoniae, Lactobacillus casei and Escherichia coli. The indigenous fungi isolated and identified were Saccharomyces cerevisiae and Mucor circinelloides. There were variations in bacteria found having Lactobacillus casei dominating. Among these indigenous organisms, Saccharomyces cerevisiae had the ability to withstand the pH and ethanol content. The pH decreased from 5.0-3.0, total suspended solids decreased from 314.50ppm-104.00ppm, total dissolved solids increased from 0.40ppm-650.00ppm. Total reducing sugar was 38.90. This study reveals that indigenous bacteria during the production of bioethanol from corncob died as ethanol production increased while fungi survived in the medium until the sugar diminished. The death of bacteria shows that ethanol is an antimicrobial agent. Hence genetic modification of the bacteria to obtain strains that can withstand these toxic substances yet produce ethanol is recommended.

Keywords: Corn cob, fermentation, bioethanol, bacterial succession, fungal succession.