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Chemical Engineers Convert
Plant Sugars Into Renewable Diesel
Engineers from the MIT were able to
genetically reprogram a strain of yeast to
convert sugars to fats more efficiently.
Engineers from the MIT were able to
genetically reprogram a strain of yeast
to convert sugars to fats more efficiently.
This advance could lead to the renewable
production of high-energy fuels such as
diesel.
The researchers were led by Gregory
Stephanopoulos the Willard Henry Dow
Professor of Chemical Engineering and
Biotechnology at MIT. They modified the
metabolic pathways of year that naturally
produces large quantities of lipids to make
them 30 percent more efficient.
According to Stephanopoulos, “We have
rewired the metabolism of these microbes
to make them capable of producing oils at
very high yields,”
With this upgrade, the production of
renewable high-energy fuels can now be
economically feasible. Today the research
team is working on additional improvements
that can help get closer to that goal. “What
we’ve done is reach about 75 percent of this
yeast’s potential, and there is an additional
25 percent that will be subject of follow-up
work,” Stephanopoulos adds.
There are renewable fuels that are made
from corn and are useful as gasoline
additives for running cars, but for large
vehicles like ships, trucks and airplanes,
more powerful fuels such as diesel are
needed. “Diesel is the preferred fuel
because of its high energy density and
the high efficiency of the engines that run
on diesel. The problem with diesel is t hat
so far it is entirely made from fossil fuels.”
Stephanopoulos said.
There have been efforts to develop engines
that run on biodiesel that are made from
used cooking oil and had some success.
Unfortunately, cooking oil is a scarce and
expensive fuel source. On the other hand,
starches like sugar cane and corn are much
cheaper and more abundant. However, they
should first be converted into lipids and will
then be turned into high-density fuels such
as diesel.
To be able to achieve this product, the
research team worked with a yeast named
Yarrowia lipolytica, which is a yeast that
naturally produces large quantities of lipids.
The team focused on utilizing the electrons
that are generated from the breakdown
of the glucose. They then transformed
Yarrowia with synthetic pathways that
convert surplus NADH, which is a product
of glucose breakdown, into NADPH, which
can be utilized to synthesize lipids. They
then ended up testing more than a dozen
modified synthetic pathways.
By using this pathway, the yeast cells will
only require only two-thirds of the glucose
that is needed by unmodified yeast cells
to produce the same amount of oil. The
researchers hope to make this process even
more efficient than when using cornstarch.
They are also searching for cheaper
sources of plant material such as grass and
agricultural waste.
Oil & Gas Leaders • April 2017 23