US engineers reprogram yeast for efficient conversion of plant sugars into oils

Researchers from the Massachusetts Institute of Technology (MIT) in the US have genetically reprogrammed a strain of yeast, allowing it to more efficiently convert plant sugars into oils.

The reprogramming of yeast could make possible the renewable production of high-energy fuels such as diesel.

The team said that they modified the metabolic pathways of yeast which allows natural production of large quantities of lipids, making them about 30% more efficient.

MIT Chemical Engineering and Biotechnology Willard Henry Dow Professor Gregory Stephanopoulos said: “We have rewired the metabolism of these microbes to make them capable of producing oils at very high yields.”

In a project, which is funded by the US Department of Energy, the team worked on yeast, known as Yarrowia lipolytica, which produces large quantities of lipids naturally.

In order to fully utilize the electrons generated from the breakdown of glucose, the researchers have transformed Yarrowia with synthetic pathways that convert surplus NADH, a product of glucose breakdown, to NADPH, which can be used to synthesize lipids.

The team continued to test more than 12 modified synthetic pathways.

Stephanopoulos added: “It turned out that the combination of two of these pathways gave us the best results that we report in the paper.

“The actual mechanism of why a couple of these pathways work much better than the others is not well-understood.”

The researchers said that the improved pathway allows the yeast cells to use only two-thirds of glucose required by unmodified yeast cells to produce the same amount of oil.

Stephanopoulos said: “There is still room for more improvement, and if we push more in this direction, then the process will become even more efficient, requiring even less glucose to produce a gallon of oil.”

MIT team said they are advancing the research work to further make production of renewable high-energy fuels economically feasible.

Image: MIT researchers tested more than 12 modified synthetic pathways on yeast. Photo: courtesy of Jose-Luis Olivares/ Massachusetts Institute of Technology (MIT).