It has been used for millennia in baking and brewing, and now budding yeast  (Saccharomyces cerevisiae) also could take on the role of a feedstock for producing fuels, chemicals, and proteins, according to Jens Nielsen, a systems and synthetic biologist at Chalmers University of Technology in Gothenburg Sweden.

With growing food shortages and prices rising throughout the world, using food crops to produce ethanol simply is not going to be a viable option, he told a symposium on industrial metabolism at the AAAS Annual Meeting. “In the long run will we have to go to biomass, a second-generation processes where we use other than food crops.”

Many agree with that assessment and are striving to develop their own platforms to generate biofuels and chemical feedstocks. Perhaps the biggest is the $600 million partnership between petrochemical giant Exxon and genomics wiz J. Craig Venter. It is tweaking the genes in algae to produce biofuel in a pilot plant being built in Southern California.

Yeast is Nielsen’s choice as a platform to deliver a range of fuels, chemicals, and proteins. Archaeological evidence of the versatile organism being used in breads and brewing dates back to at least 4000 B.C. in Egypt.

He said much of the basic science of understanding the organism and how to manipulate it already has been carried out with the support of the U.S. National Institutes of Health and other health investors. His group has modified yeast through genetic engineering to change the metabolism of the cells and produce desired chemical feedstocks in greater quantities.

Nielsen fears that the greatest impediment to commercializing developments such as this is an unfair comparison with what can be done with Brazilian sugar cane, “which is just so cheap” that alternatives do not seem attractive. He said the apt comparison is with the cost of oil and more expensive alternatives.  

Given the progress being made in synthetic biology, “in the future we may be able to design [an organism] in silico and then improve or create the new platform” by understanding which parts of the metabolism has changed, Nielsen said.

His group has achieved some success in identifying three genes in yeast that can greatly increase production of succinic acid, a molecule that can serve as a building block for high-value biobased chemicals. Ordinary yeast requires glycine to produce the acid, but through serial passages of the organism in lower and lower concentrations of glycine, they were able to create yeast that did not need glycine to produce succinic acid.

Nielsen believes the greatest need in the field today is computational tools that are tailored for industrialized application of synthetic biology products. They likely could be adapted from modeling and simulation tools used to predict the weather and other complex interactions.

We need to be able to “take all of this information and pinpoint and use it in directed ways,” he said. “What are we going to engineer? What are we going to change? That is not a trivial  question because you often are talking about many different enzymes and pathways.”