Abstract:
The purpose of this study is to improve the conversion efficiency of lignocellulose to ethanol. This was achieved by converting the hemi cellulosic sugar xylose to ethanol. In this research a xylose fermenting bacteria was isolated from local soil sample. By performing different biochemical tests the isolated bacteria was found to be identical to Bacillus subtilis. The optimum fermentation conditions at 150 rpm for 48 h in a shake flask are as follows: pH 7.0, reducing sugar 78 gL-1, inoculation amount 3% and temperature 37oC. The results indicated that a xylose to ethanol yield coefficient of 24% was achieved. At the same time the effect of different sugar concentrations was studied by making different mixtures of xylose and glucose. As a result, the bacteria’s ability to ferment xylose was found to be greater than to ferment glucose. The isolation, preservation and usage of isolated Bacillus subtilis can help improve the conversion process of hemicellulose sugar such as xylose to produce ethanol.
