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UD researcher finds bacteria cells progress toward optimal behavior

University of Delaware researcher Jeremy Edwards
NEWARK, DE.--University of Delaware researcher Jeremy Edwards has developed advanced computerized mathematical models that can be used to predict the evolution of bacterial cells and has found that those cells progress toward optimal behavior.

Edwards, assistant professor of chemical engineering, said the finding could have important implications in fields such as human health, energy and environmental remediation.

“If we can predict evolution, we can use these principles in design applications,” Edwards said. “Namely, we may be able to design and construct cells to perform useful tasks.”

The work being conducted by Edwards and fellow researchers from the University of California at San Diego, Rafael Ibarra and Bernhard Palsson, was described in a paper in the Nov. 14, 2002, issue of Nature.

“Our past work has utilized optimization-based models of whole cells to calculate the metabolic behavior of bacteria,” Edwards said.

The research team works with the Escherichia coli bacteria–the same E. coli that is often in the news for outbreaks of food poisoning–because it is one of the most-studied organisms on the planet and as such there is a large quantity of data from which to construct models.

Borrowing a phrase from Charles Darwin, the father of evolutionary theory, Edwards said the team worked from the notion that “this is what the cell has, so now what is the best it can do in terms of natural selection or the survival of the fittest.

“We were extremely successful with the predictions; however, I wondered whether cells always behaved optimally,” Edwards said, adding that the latter notion first struck him while a postdoctoral fellow at Harvard University. “For example, what if the cells had never seen a condition before? I figured that there would be no reason to believe that the behavior would be optimal.

“We decided to take E. coli and put it into environments it had not seen before,” Edwards said. “The key question was, can you predict how it will evolve?” The answer was a resounding yes.

Edwards said the findings in the paper published in Nature “clearly show that cells do behave non-optimally in some conditions, and the great importance of the paper is that we show that we can use mathematical models to predict the evolution of bacterial cells and that the bacterial cells evolve toward optimal behavior.”

Being able to predict how cells evolve in a laboratory over time is a “big stretch from predicting the evolution of complex cellular life as we know it,” Edwards acknowledged, but he said the results are nonetheless extremely valuable.

The findings “open up many future possibilities,” Edwards said. “For example, if we can predict evolution, we can use these principles in design applications. Namely, we may be able to design and construct cells to perform useful tasks in bioremediation, protein production, pharmaceutical production and the production of bio-fuels.”

“To rationally engineer a cell is nearly impossible,” Edwards said. “If you understand how the genetic makeup will behave in certain conditions, that is a start. You can use that as an engineering and design principle to begin engineering cells to do certain things.”

The project has National Science Foundation funding, and Edwards has received a grant from the U.S. Environmental Protection Agency to study the possible use of radiation-resistant bacteria to degrade toxic chemicals, such as benzene and toluene, at hazardous waste dump sites.

In addition, he would like to use the findings in human health research, particularly cancer, in which he said “renegade cells optimize without regard for the entire organism.”

The range of potential uses is broad and Edwards said he believes there are uses he has not yet considered. “This should be interesting to people in all kinds of fields,” he said, “people who can develop applications I don’t even see.”

Contact: Neil Thomas, (302) 831-6408

Jan. 9, 2002