Processes of Darwinian evolution are fundamental to understanding biological form and function, but are difficult to appreciate on the human timescale. Over the past decade, methods have been developed for evolving biological macromolecules in the laboratory, including a system for the continuous in vitro evolution of RNA enzymes (ribozymes). This system currently offers the most realistic laboratory model of biological evolution, but has been limited by the cost of reagents, the amount of time and labor needed to evolve interesting biomolecular properties, and the imprecise manner in which the evolving population is maintained. Recently, a novel approach for continuous evolution has been developed that employs microfluidic technology. It allows evolution to be carried out in an automated fashion under computer control, with continuous monitoring of the population size and precise control over critical parameters such as mutation frequency and selection pressure. This project is exploiting microfluidic-based evolution to address key questions concerning macromolecular evolution, in particular, the role of genetic diversity in escaping evolutionary bottlenecks, the ability of an enzyme to optimize its affinity and specificity for a particular substrate, and the maximum frequency of mutation that can be tolerated by an evolving population. In addition, the microfluidic system is being developed as an assay platform for the detection of small molecule and protein targets. The broader aim of the project is to make Darwinian evolution a tangible process that one can literally hold in their hand, and that can be operated much like one would operate a computer program.
