By Gary Thomas
Researchers have developed a novel strain of yeast using gene shuffling to improve the production of bioethanol.
Bioethanol is a clean and renewable form of energy and is considered as a replacement for fossil fuel. Production of bioethanol requires glucose and conventional methods utilize glucose derived from starch and sugar crops. These crops can also be used for food hence, using these products affects the availability of food. Xylose, a plant sugar, is a potential alternative and is available in large quantities in wood and agricultural waste. Certain yeasts can ferment xylose but they are not efficient at production of ethanol, while, yeasts that can efficiently produce ethanol are not able to ferment xylose or other pentose sugars.
Using gene shuffling process, the researchers integrated P. Stipitis genomes that are tolerant to xylose and S. Cerevisiae genomes that are tolerant to ethanol. However, S. Cerevisiae is not tolerant to xylose. The P. Stipitis genome was initially transferred into S. Cerevisiae and specific recombinant strains were chosen based on two factors. First, their capability to grow on xylose was considered and then their ability for ethanol production was considered. The genes were shuffled in two rounds, and in the second round, the best of the strains was selected and the S. Cerevisiae genome was transferred into it. The strains that were obtained were then checked for tolerance of ethanol.
The hybrid yeast that was produced was able to produce bioethanol from xylose and also survive in ethanol, even under high concentrations. The researchers measured xylitol, the by-product derived during xylose fermentation, and found that the hybrid strain to be better at producing ethanol using xylose.
The study was performed by researchers at the Ngee Ann Polytechnic in Singapore. The research has been published in Biotechnology for Biofuels, the open access journal from BioMed Central.