Collaboration to re-engineer common fermentative yeast

By Jessica Ebert
A team of scientists at the University of California, Irvine (UCI) has joined with CODA Genomics, an Orange County-based company that provides genetic engineering solutions, to improve the efficiency of a commonly used strain of yeast for the production of ethanol. CODA stands for computationally optimized DNA assembly.

The $1.6 million collaboration, sponsored by CODA with a matching grant from UCI, aims to engineer a strain of the yeast Saccharomyces cerevisiae that can quickly and efficiently ferment glucose, as well as five-carbon sugars like xylose and arabinose, which the yeast doesn't utilize naturally. Although there are commercially available strains that have been engineered to ferment pentose sugars, the process isn't very efficient, said G. Wesley Hatfield, a UCI molecular biologist and cofounder of CODA. "One of the problems with the current production strains that are being used commercially is that the enzymes that have been engineered into the yeast are not catalytically effective," he said. "They don't work as fast and are not expressed as well as they could."

To improve on this, Hatfield's team applies its patented CODA technology to the problem. Its computationally optimized DNA assembly technology employs a supercomputer that uses thermodynamic principles and sophisticated algorithms to predict DNA sequences that self-assemble into genes that produce enzymes with greater activities that are expressed at higher levels. Those genes can be synthesized in the laboratory and inserted into the yeast. The activities of the enzymes are monitored, and the structure of the proteins is modeled. Using these models, Hatfield's team can predict changes that need to be made to improve the activities of these enzymes. "We believe that we can use this technology to overcome the past obstacles to metabolically engineering yeast, so they will be able to process the hexose sugars better and for the first time efficiently process pentose sugars," Hatfield said. "We expect to increase the production of ethanol by four- to fivefold."