DURHAM, N.C. -- As scientists work toward making genetically altered bacteria create living "circuits" to produce a myriad of useful proteins and chemicals, they have logically assumed that the single-celled organisms would always respond to an external command in the same way.
Alas, some bacteria apparently have an individualistic streak that makes them zig when the others zag.
A new set of experiments by Duke University bioengineers has uncovered the existence of "bistability," in which an individual cell has the potential to live in either of two states, depending on which state it was in when stimulated.
Taking into account the effects of this phenomenon should greatly enhance the future efficiency of synthetic circuits, said biomedical engineer Lingchong You of Duke's Pratt School of Engineering and the Duke Institute for Genome Sciences & Policy.
In principle, re-programmed bacteria in a synthetic circuit can be useful for producing proteins, enzymes or chemicals in a coordinated way, or even delivering different types of drugs or selectively killing cancer cells, the scientists said.
Researchers in this new field of synthetic biology "program" populations of genetically altered bacteria to direct their actions in much the same way that a computer program directs a computer. In this analogy, the genetic alteration is the software, the cell the computer. The Duke researchers found that not only does the software drive the computer's actions, but the computer in turn influences the running of the software.
"In the past, synthetic biologists have often assumed that the components of the circuit would act in a predictable fashion every time and that the cells carrying the circuit would just serve as a passive reactor," You said. "In essence, they have taken a circuit-centric view for the design and optimization process. This notion is helpful in making the design process more convenient."
|Contact: Richard Merritt|