SCREENING OF FACTORS RESPONSIBLE FOR CONVERSION OF MAIZE STRAW INTO BIOETHANOL

Bioethanol

Abstract

Maize straw is a lignocellulosic waste that is annually added to the environment as pollutant because its accumulation constitutes a nuisance and in addition, its reducing sugar is not readily released. Pretreatment of maize straw makes its reducing sugar available for fermentation into bio-products such as bioethanol production under optimized conditions. This work aimed at determining the effect of different parameters on ethanol production by Saccharomyces cerevisiae from pretreated maize straw. Effects of pH, temperature, sugar concentration, nitrogen source, and inoculum load/sizes on ethanol yield of pretreated maize straw by S. cerevisiae SA01 and S. cerevisiae SA02 for optimum ethanol production were determined using standard methods. Ethanol content was estimated using a gravimetric method. The optimum ethanol production (1.97 g/L) was obtained at pH 5.5 while highest ethanol content (2.76 and 2.37 g/L) was at 30 °C by S. cerevisiae SA01 and S. cerevisiae SA02, respectively. The glucose concentration of 2 % supported the highest ethanol production (3.95 g/L) by S. cerevisiae SA02. Corn steep liquor was the best among the nitrogen sources used and increased the ethanol yield of S. cerevisiae SA01 and S. cerevisiae SA02 by 300 and 661 %, respectively. One percent of 1.0 MacFarland standard of both yeasts supported the highest ethanol production (14.99 g/L) from pretreated maize straw. Bio-conversion of maize straw to substrate for bioethanol production at optimized conditions will reduce environmental pollution, production cost and increase energy sources.