Simple Tools for Rapid Measurements of Evolving Fitness Distributions

Optimizing genetic engineering requires detailed knowledge of how fitness is distributed among populations of organisms or gene variants. But measuring even simple distributions of fitness requires characterizing the activity of thousands of individual variants, typically only possible with genes that produce a visible signal. Through the introduction of fluorescent genes, we show how cytometry can be used to measure the distribution of fitness for a wide range of genes. Additional analysis highlights other tools for approximating fitness distributions, and shows how these measurements can directly improve protocols for directed evolution.