Synthetic biology gives ecosystem clues

Bioengineers have used genetically altered bacteria to provide new insights into how the complex relationship of predator and prey.

A whole ecosystem in a petri dish? Lingchong You thinks with a spot of genetic reprogramming it is possible

By loading new ‘programming’ into bacteria to make them perform new functions, US researchers FROM Duke University rewrote the genetic code of Escherichia coli to form a mutually dependent living circuit of predator and prey.
The bacterial predators don’t actually eat the prey, however. The two populations control each others’ suicide rates.

“We created a synthetic ecosystem made up of two distinct populations of E. coli, each with its own specific set of programming and each with the ability to affect the existence of the other,” said Lingchong You, Assistant Professor of biomedical engineering at Duke’s Pratt School of Engineering. “This ecosystem is quite similar to the traditional predator-prey relationship seen in nature and may allow us to explore the dynamics of interacting populations in a predictable manner.”

This field of study, known as synthetic biology, emerged almost a decade ago, and many of the systems created since have involved the reprogramming of single bacteria. The current circuit is unique in that two different populations of reprogrammed bacteria live in the same ecosystem and are dependent on each other for survival.

“The key to the success of this kind of circuit is the ability of the two populations to communicate with each other,” You said. “We created bacteria representing the predators and the prey, with each having the ability to secrete chemicals into their shared ecosystem that can protect or kill.”

In this system, low levels of prey in the environment cause the activation of a ‘suicide’ gene in the predator, causing them to die. However, as the population of prey increases, it secretes into the environment a chemical that - when it achieves a high enough concentration - stimulates a gene in the predator to produce an ‘antidote’ to the suicide gene. This leads to an increase in predators, which in turn causes the predator to produce another chemical which enters the prey cell and activates a ‘killer’ gene, causing the prey to die.

“This system is much like the natural world, where one species - the prey - suffers from growth of another species - the predator,” You said. “Likewise, the predator benefits from the growth of the prey.”
The results of the study appear in the journal Molecular Systems Biology.