This research seeks to initiate a multi-disciplinary
collaboration to maximize ethanol production by
metabolically engineered Zymomonas mobilis strains from
mixtures of hexose and pentose sugars through the
application of metabolic flux control techniques. A
collaborative research is proposed between the Principal
Investigator, a biochemical engineer skilled in the
mathematical modeling of recombinant microorganisms at the
University of Colorado, Boulder and two Collaborating
Investigators at the Biotechnology Branch of the National
Renewable Energy Laboratory (NREL) in Golden, Colorado.
The scientists at NREL have successfully engineered the
ethanol fermenting Zymomonas mobilis to broaden its
substrate utilization range from only the hexoses, glucose
and fructose, to include the additional pentose sugars,
xylose and arabinose, found in renewable biomass feedstocks
and agricultural residues. The pentose fermentation was
accomplished by introducing two genes encoding for key
enzymes in the xylose assimilation pathway, three genes
encoding for key enzymes in the arabinose assimilation
pathway and two genes encoding for key enzymes in the
pentose phosphate pathway into the efficient ethanol
producer Z mobilis.
In the proposed research, detailed kinetic models of the
integrated pathways will be developed to identify potential
sites for enhancing the overall ethanol metabolic flux.
Intracellular metabolic intermediates will be measured using
powerful non-invasive, real-time analytical tools to
identify bottlenecks and investigate the predictions from
our kinetic model simulations. New genetic engineering tools
will be developed in Z mobilis, and improved strains will be
constructed for efficient ethanol fermentation from hexose
and pentose sugar mixtures, found in biomass and
agricultural residues.
