Current research efforts are focused on 'second generation biofuels', which includes biofuels produced from lignocellulosic material. Lignocellulosic material is primarily composed of cellulose, a glucose polymer, xylose rich hemicellulose and non-fermentable lignin. Saccharomyces cerevisiae is widely used on an industrial scale for the production of ethanol from glucose; however, native S. cerevisiae does not contain the genes required for fermentation of xylose into ethanol. Others have sequentially expressed trans-genes from xylose fermenting organisms to engineer strains of S. cerevisiae capable of fermenting this pentose. The goal of this thesis was to generate a single cassette of 9 genes which have been shown to ferment xylose and arabinose. The 17 kb DNA fragment harboring all the genes necessary was introduced into the yeast genome using one-step homologous recombination based transformation. Expression of this cassette was verified by demonstrating that the first and last genes on this cassette were transcribed. The modified strain exhibited xylose utilization under microaerobic fermentation conditions. Further genetic and process engineering methods may be employed to improve the yield. The experiments described here demonstrate that generating a functional cassette of pentose fermenting genes is still achievable.
Worcester Polytechnic Institute
Biology & Biotechnology
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Swana, Jeffrey Ross, "Construction and Analysis of a Modified Yeast Strain for Next Generation Biofuel Production" (2013). Masters Theses (All Theses, All Years). 52.
fermentation, yeast, genetic engineering, lignocellulose, biofuels