ASGSB 2003 Annual Meeting Abstracts
COMPUTATIONAL MODELING OF EXTRACELLULAR MASS TRANSPORT.
M.R. Benoit1, D.M. Klaus1, and E.S. Nelson2.
1Dept of Aerospace Engineering Sciences,
at Boulder. 2Computational Microgravity Laboratory, NASA Glenn
Research Center, Cleveland, OH.
Spaceflight has been shown to induce various alterations in the growth
kinetics of bacterial cultures, including shortened lag phase and higher final
cell population density. The specific causal mechanisms for the differences
between flight and ground control samples, however, have yet to be positively
determined. It has been proposed that changes in the fluid environment
immediately surrounding the cell (as a consequence of altered mass transport
processes similar to those governing protein crystal growth) may be indirectly
responsible for the unique microbial responses observed to occur in space.
The objective of the present study is to establish a mathematical model
incorporating the essential relationships influencing extracellular mass
transport that are thought to affect microbial metabolism. The model should
predict specified parameters relevant to altered growth kinetics under varying
levels of gravity. The linear momentum equation and species concentration
equations for nutrients and byproducts that govern mass transport have been
applied to a test case of E. coli cultured in minimal growth media.
Solutions have been obtained using the continuum mechanics solver COMET™.
The model currently generates a buoyant plume of less dense metabolic
byproducts in a 1g simulation. The velocity of the plume compares favorably to
previous experimental and quantitative theoretical work. Initial results
suggest that numerical analysis can serve as a valid tool for studying the
complex interplay of forces and resultant mass transport phenomena that act on
Future plans include incorporation of multiple interacting microbes,
extending the problem to 3-D, increasing sophistication of the metabolic
model, and adding microbial movement, including Brownian motion, sedimentation
and random (swimming) motility.
(Supported by NASA: NGT5-52386)
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