Oscillators are a fundamental building block in many engineering fields and are a widespread phenomenon in biology. Building a biological oscillator is thus a crucial step forward in the field of Synthetic Biology.
Engineering a Molecular Predation Oscillator, the iGEM project 2006 of Imperial College London, provides a new approach to create a stable biological oscillator: It follows an engineering-based cycle of specification, design, modelling, implementation and testing/validation. The innovative design of the oscillator relies on predator-prey dynamics based on the Lotka-Volterra model.

Following the design of the oscillator, a full theoretical analysis of the Lotka-Volterra properties was carried out, which promised the successful outcome of oscillations. Additionally, all components as well as the overall oscillator were modelled such that the behaviour of the system could be predicted. Our team successfully built functional parts, thus providing the building block for the final oscillator. All parts created were experimentally tested and their characterization could be used to feedback information into the modelling.

1) Specifications:

• Stable and robust oscillations
• Controllable frequency/amplitude
• Generic and modular

2) Design:

• Mimics predator-prey dynamics based on the Lotka-Volterra model

3) Modelling:

• Full theoretical analysis
• Modelling of the full system

4) Implementation:

• All parts designed
• 4 functional & 5 intermediate submitted to the Registry

5) Testing/Validation:

• Successful characterization of sub-components.

As a method of controlling the activation of the positive-feedback loop in our predator-prey based oscillator, we successfully created this part, which can be used as a general Pops Blocker:

• This part is placed downstream of a promoter and prevents any Pops from the promoter passing through this part
• When an accompanying Cre Recombinase plasmid becomes activated, the enzyme produced will permanently cut a section of DNA from the plasmid containing this part
• Only then, the polymerase can pass through this part and transcribe downstream genes.

We also worked on a Biosensor for measuring AHL concentrations in order to establish a Biological to Electrical Interface this summer.

• Using an enzyme to hydrolize the lactone AHL would result in a local change in pH
• Measuring the change in pH gives a measurement of how much AHL is present.