Creating an oil yeast from brewing yeast

Engineering microorganisms for sustainable production of fuels and chemicals are attractive because it is a renewable process and has potential to replace fossil based production.The cost-efficient production of fuels and chemicals needs to achieve high yields with low by-product production,which requires high metabolic flux toward the desired products.However,microorganisms have evolved robust natural habitat,and their tight regulation of metabolism make it challenging to rewire the flux[1].For instance,as a potential cell factory,Saccharomyces cerevisiae has been engineered for the production of a variety of fuels,chemicals,and pharmaceuticals,whereas the inherent ethanol production hinders the overproduction of desired chemicals.S.cerevisiae is a Crabtree-positive organism,and ethanol production is prodominate even under aerobic condition when glucose is in excess[2].Completely blocking ethanol production leads to growth defects when using glucose as the sole carbon source,due to the lack of cytosolic acetyl-CoA for synthesis of cellular essential components such as lipids[2].Therefore,it is very difficult to completely redirect the flux from ethanol accumulation toward the product of interest only through rational engineering.Recently,the group headed by Professor Jens Nielsen at Chalmers University of Technology,who has pioneered on yeast synthetic biology,solved this through combining metabolic engineering with adaptive evolution,which resulted a synthetic oil yeast with high fatty acid production and abolished ethanol accumulation[3].This study represents an important milestone in engineering of yeast for production of fuels,chemicals,and pharmaceuticals and shows the great potential metabolic engineering in rewiring the natural metabolic networks.