Genetic Engineering of Yeast For Efficient Biofuel Production
The global biofuels market is expected to rise from $82.7 billion in 2011 to $185.3 billion in 20211. Genetic engineering paves its way towards efficient biomass conversion into biofuel through metabolic manipulations2,3,4,5. Present article is an effort to explore the role of Biotechnology engineering in Yeast as a tool towards efficient production of bioethanol through economically comprehensive routes. Glucose and Sucrose (derived from cane juice, etc.) are the conventional Yeast substrates for bioethanol production6,7,8. However, efforts have been made to exploit other carbon sources as Yeast substrates like Lignocellulose, and Glycerol (by-product of biodiesel synthesis) for biofuel production8,9,10,11,12. But, generation of toxic by-products during metabolic pathways13,14,15 coupled with unability to metabolise certain polymers (like pentose sugars i.e. Xylose, Arabinose)16 are the key issues need to be addressed. Genetically engineered Yeast (Saccharomyces cerevisiae) easily assimilates pentose sugar through alternative pathways. US biotechnologists developed a pathway of simultaneous breakdown of Xylose and converts Acetic acid (toxic for Yeast cells) into fuel17,18. During alcoholic fermentation by Yeast, all sugars are not converted into ethanol; instead some amount is also lost in the form of glycerol19, thus reduces the efficiency of bioethanol production. However, scientists overcome this problem through genetic engineering of Yeast through introduction of RUBISCO enzyme (from a CO2-fixating bacterium) and spinach gene for efficient utilization of CO2 and reduction in the formation of glycerol20. A/c to Stephanopoulos, the toxic effect of high ethanol doses on yeast is the biggest limitation on cost-effective bioethanol production15. Scientists progressively worked on increasing the production of biofuels through various strategies like by increasing the yeasts cells tolerance using potassium and an acidity-reducing compound15,21. Scaling up such type of techniques would results in reduction of biofuel cost. However, efforts are required to translate such laboratory accomplishments to an industrial setting with large scale batch fermentation.
Key words: Biofuels, Bioethanol, Yeast, Biotechnology, and Genetic engineering.