I came across these two stories which were amazingly similar:

UC Irvine scientists want to bioengineer yeast to increase sugar metabolism from 20% to 80%.
Researchers at UCI’s Institute for Genomics and Bioinformatics (IGB) are using CODA Genomics’ patented gene-protein-production algorithms to tweak the genetic structure of Saccharomyces, which has the potential to efficiently turn natural materials into ethanol – a clean and environmentally safe fuel.

Saccharomyces produces ethanol as a byproduct when it ferments sugars found in plant materials. In its natural state, the yeast processes the glucose that grows in these materials, but does not contain the necessary enzymes to process other sugars in biomass, such as xylose and arabinose. The bio-engineered version of the yeast will produce enzymes that can help it digest other sugars easily, maximizing its ethanol production.

Scientists believe the bio-engineered yeast could use 80-90 percent of the sugars in biomass for ethanol production, up from about 20 percent with current technologies.

“We’re trying to build a better yeast strain – one that can produce more ethanol from the same amount of biomass by breaking it down naturally,” said G. Wesley Hatfield, UCI professor emeritus and CODA Genomics co-founder.
Mitsui Engineering develops special yeast that increases ethanol output from 5 to 20 grams per liter of raw material
The unique process involves the use of a special yeast developed in-house for the fermentation of sugars extracted from cane and other raw materials. Efficiency is enhanced through new techniques that allow the yeast to remain active in fermentation tanks even under high temperatures and other extreme conditions.

As a result, bioethanol output per liter of raw material is increased to 20 grams from about 5 grams now. The firm has completed work on the design of the production system and is ready to begin shipping it after conducting tests.
Current processes are inefficient because as the enzymes produce ethanol, they end up killing themselves. These two articles suggest that scientists have bioengineered yeast that will live longer in the fermentation process -- the yeast keeps converting sugar into ethanol even though it is swimming in a sea of ethanol.

All estiamtes are that the U.S.A. will be able to replace 30% of its gasoline with cellulosic ethanol. If this yeast can quadruple the output, we will have all of the ethanol we can use.