With
metabolically engineered microorganisms hungry for levulinic acid rather than
sugar, a University of Wisconsin-Madison (UW-Madison) chemical and biological
engineer aims to create more sustainable, cost-effective processes for
converting biomass into high-energy-density hydrocarbon fuels.

Currently,
commercial biofuels—for example, ethanol and biodiesel—are produced from such
crops as sugarcane or corn, or derived from plant oils. However, existing
production processes for these “first-generation” biofuels are energy intensive
and ill suited to meet future demand for alternative transportation fuels.

Brian Pfleger, a
UW-Madison assistant professor of chemical and biological engineering, is among
an emerging group of researchers that is capitalizing on modern biotechnology
tools to engineer systems that efficiently and sustainably produce “drop-in”
fuels—advanced biofuels interchangeable with today’s fuels and compatible with
existing infrastructure.

A synthetic
biologist, Pfleger received a prestigious Faculty Early Career Development (CAREER)
award from the National Science Foundation to support his research. With the
award, Pfleger will study, engineer, and test metabolic pathways in bacteria
that can convert biomass to hydrocarbon fuels in a process that bypasses the
difficult intermediate step of breaking down the natural sugars in plants.

Those sugars
have a tendency to degrade into levulinic acid, which the U.S. Department of
Energy calls one of the top value-added chemicals from biomass. Exploiting that
tendency, Pfleger will engineer an organism—for example, by adding or
subtracting genes—that quickly and efficiently can break down levulinic acid
into smaller molecules known as free fatty acids that, in turn, can be used to
produce fuels and chemicals. This work complements advanced biofuel production
research he has conducted at UW-Madison through the Great Lakes Bioenergy
Research Center.

Pfleger’s
research also leverages the expertise of colleague James Dumesic, the Steenbock
Professor of Chemical and Biological Engineering at UW-Madison who has made
groundbreaking advances in using catalysts to convert levulinic acid into
high-energy liquid fuels. However, capitalizing on the power of synthetic
biology, Pfleger can tailor microorganisms that can produce specific—or a wider
range—of fuels and chemicals.

“In a catalytic
sense, you make a mixture of things; a microbe makes a particular compound,” he
says.

Source: University of Wisconsin-Madison