Powerful Microbial Base-Editing Toolbox: From Optimization Strategies to Versatile Applications.

Base editors (BE) based on CRISPR systems are practical gene-editing tools which continue to drive frontier advances of life sciences. BEs are able to efficiently induce point mutations at target sites without double-stranded DNA cleavage. Hence, they are widely employed in the fields of microbial genome engineering. As applications of BEs continue to expand, the demands for base-editing efficiency, fidelity, and versatility are also on the rise. In recent years, a series of optimization strategies for BEs have been developed. By engineering the core components of BEs or adopting different assembly methods, the performance of BEs has been well optimized. Moreover, series of newly established BEs have significantly expanded the base-editing toolsets. In this Review, we will summarize the current efforts for BE optimization, introduce several novel BEs with versatility, and look forward to the broadened applications for industrial microorganisms.