March 14, 2007 — Researchers at
Whitehead and MIT have engineered a new strain of yeast
that can tolerate elevated levels of both ethanol and
glucose while producing ethanol faster than other strains.
What type of yeast did they start with? How did they
engineer that yeast to achieve the desired result?
—Connie Boon, student
Response
by Hal Alper
Visiting scientist
The yeast used for this experiment was a standard laboratory
strain of the budding yeast Saccharomyces cerevisiae
which has been designed to ease genetic engineering
efforts. This strain serves as a model system which
allows for researchers to explore ideas and engineering
concepts; however is not the same type of yeast typically
used in most industrial processes or even household
uses such as making bread. As a result, we are currently
looking at expanding the results of this work to the
more complex, industrial yeasts which are commonly found
in traditional fermentation processes.
This work created and employed a generic approach to
engineering cellular systems. Every type of cell contains
a set of proteins which controls the overall level of
transcription within a cell. These proteins act as the
conductors at an orchestra by controlling which genes
get turned on and to what extent. As such, these proteins
can be engineered (by mutating them) to alter the levels
at which all these genes are transcribed. This subsequent
alteration in global gene expression gives rise to novel
phenotypes, such as the ethanol and glucose tolerance
obtained in this work. By searching through libraries
of these mutant proteins, strains with other types of
traits can be found as well.
