Evaluation of Ethanol Production from Pito Mash using Zymomonas Mobilis and Saccharomyces Cerevisiae

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This study investigated bioethanol production by means of fermentation using Zymomonas mobilis and Saccharomyces cerevisiae isolated from freshly tapped palm wine. Pito mash(waste from sorghum brewing with no appreciable value to industries or competitive use as food) was examined as alternative and cost-effective feed stock for the production of bioethanol. The parameters of ethanol fermentation, such as initial pH of the fermentation medium, temperature and period of fermentation were studied. Saccharomyces cerevisiae was tentatively identified using their morphological characteristics and by determining their pattern of fermentation and assimilation of glucose, sucrose, maltose, lactose. On the other hand, Zymomonas mobilis was identified using APITM test kit. Analysis of reducing sugar residue was performed using Dinitrosalisilic acid (DNS) method, while analysis of ethanol content was performed using gas chromatography. Pito mash recorded total starch content of 6.69 %, reducing sugar content of 11.1 mg ml-1 and cellulose content of 0.41 mg g-1.Sacchariffication by malting produced reducing sugar content of 19.75 mg ml-1. The results revealed that an initial pH of 6.0, temperature of 30oC and fermentation time of four days were the optimum conditions for S. cerevisiae while the optimum condition for Z. mobilis were pH of 5.5, temperature of 35oC and fermentation time of 3days. The maximum ethanol yield of 3.03 g l-1 and efficiency of 62% was obtained for S. cerevisiae while yield of 3.63g l- 1 and efficiency of 74.2% was obtained for Z. mobilis. Z. mobilis may be better organism for ethanol production from pito mash.
A thesis Submitted to the Department of Biochemistry and Biotechnology in Partial Fulfilment of the Requirements for the award of Master of Science (Msc) Honours Degree in Biotechnology March, 2013