Improving and repurposing biocatalysts via directed evolution

•Directed evolution has become a proven method to engineer biocatalysts’ overall performance.•New library creation and screening approaches are at the base of directed evolution.•Directed evolution is being applied to engineer natural and artificial enzymes for abiological reactions. Over the last two decades, directed evolution has become a staple in protein engineering and ushered in a new era of industrial biocatalysis. Directed evolution has provided the tools to not only improve the activity of known biocatalysts, but also to endow biocatalysts with chemical reactivities not previously encountered in nature. Here we will discuss the recent successes in the quest to enhance thermostability, stereoselectivity and activity of biocatalysts, as well as to create novel enzymes, over the last two years.