NSF PR 02-92 - November 14, 2002
The two images show how E. coli bacteria
in a laboratory evolved over time to metabolize and
grow at a rate predicted by a computer simulation.
The bottom left axis represents the amount of oxygen
that the bacteria consumed, the bottom right axis
represents the amount of glycerol (the food) the bacteria
consumed, and the vertical axis represents the rate
at which the bacteria grew.
The colored surfaces are called "phenotype phase planes."
They graphically represent the researchers' in silico
(computer) prediction for the possible ways in which
the bacteria could grow under specific environmental
conditions. The red shading represents faster growth
conditions, the green represents slower growth.
The red line is the "line of optimality," the optimal
growth rate predicted by the researchers' computer
model. Region 1 represents a phase where growth is
not optimal, Region 2 represents a phase where the
bacteria consume too much food and therefore have
to secrete some as byproducts of metabolism.
The white dots are measurements of how several E.
coli specimens were metabolizing food, and how fast
they were growing when the researchers tested them.
After 40 days (700 generations), the bacteria evolved
to metabolize as predicted by the researchers' in
silico model (all specimens cluster along the line
Photo Credit: Images courtesy of the Genetic Circuits
Research Group (Rafael U. Ibarra, Jeremy S. Edwards,
and Bernhard O. Palsson).
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02-92 - November 14, 2002