Figure 2. Generalized steps for carrying out a continuous evolution experiment.

A) a GOI is chosen for its predicted potential to evolve a desired activity. Often, the ability to carry out the desired activity at a low level is a promising starting point, although activities that are similar to the desired activity may be suitable as well. A host cell and a hypermutation system are also chosen at this stage. B) the researcher must design, build and test a selection or screen that is capable of enriching cells encoding GOIs with the desired function. This requires some cell-based mechanism of converting the activity of the GOI into a growth or optical signal, here symbolized as falling dominos. If available, GOI variants with known propensity for the desired activity, or ‘fitness’, may be used to test that the screen or selection is effective. C) the GOI and necessary components of the hypermutation system are encoded in the host cell. D) continuous evolution strategies are applied to evolve the desired activities. Different strategies offer different advantages and disadvantages and should be considered against each other. Labor, resources, feasible population size, durability and other factors can vary depending on the chosen strategy. E) following an evolution experiment that appears successful, GOIs contained in evolved populations should be isolated and characterized via sequencing and functional assays. The chosen approach will depend on the specific demands of the experiment and application.