Escherichia Coli Fermentation'

1
Escherichia Coli Fermentation. Tanya Phillips,
Tristan Pritchard-Meaker, Dr. Ramon Gonzolaz, Dr.
Jacqueline Shanks
Wild Type E. Coli Growth
Why Ferment E. Coli? The fermentation of E.
coli and recombinant strains of E. coli results
in the production of useful organic acids and
ethanol. Ethanol from plant biomass is valuable
because it could be used to replace fossil fuels
with renewable resources. Plant biomass sources
include agricultural residues, wood residues,
crops, and waste streams.
LY01 Growth

• Linear Phase Rate
• 1.2593 / cell mass specific rate
• The specific rate in the linear phase is
  constantly decreasing because the constant slope
  is divided by continually increasing cell mass.

• Why Examine Metabolic Fluxes?
• Examining metabolic fluxes of bacteria can
  allow us to gain a closer look at how the cell
  functions than growth rates alone can establish.
  Once a flux analysis is completed, it is possible
  to determine the movement of intermediates, which
  can help explain why the cell does what it does.

LY01 Organic Acids and Ethanol The various
mutations that occur to produce LY01(selected for
high ethanol tolerance) from KO11 by direct
evolution result in this profile in which the
succinate concentration is still zero.
The Next Step Flux Analysis SV0 SmVm ScVc
0 Vc -SmVm . Sc-1 S is the stoichiometric
matrix and V is the flux vector. S and V are
divided into measurable and calculated elements.
Wild Type E. Coli Organic Acids and Ethanol
Cell Mass and Optical Density Optical density and
dry cell mass have a linear correlation.
KO11 Growth
Metabolic Pathway Diagram (1)
Specific Rate
KO11 Organic Acids and Ethanol The elimination
of the succinate-producing gene and the addition
of ethanol-producing genes (2) lead to this
profile showing high ethanol concentration and a
succinate concentration of zero.

• References
• Karp, P.D. Riley, M. Saier, M. Paulsen, I.T.
  Collado-Vides, J. Paley, S. Pellegrini-Toole,
  A. Bonavides, C. Gama-Castro, S. The Ecocyc
  database. Nucleic Acids Res. 2002, 30,56-58
• 2. Yomano, L.P. York, S.W. Ingram, L.O.
  Journal of Industrial Microbiology
  Biotechnology. Isolation and characterization of
  ethanol-tolerant mutants of Escherichia coli KO11
  for fuel ethanol production. 1998, 20, 132-138

• Equation
• m(dx/dt)(1/x) d(ln(x))/dt
• m 1.2524
• m is the specific rate and is constant
• This equation is only valid for the
  exponential growth phase.