Genetic biosensors for small-molecule products: Design and applications in high-throughput screening

Overproduction of small-molecule chemicals using engineered microbial cells has greatly reduced the production cost and promoted environmental protection. Notably, the rapid and sensitive evaluation of the in vivo concentrations of the desired products greatly facilitates the optimization process of cell factories. For this purpose, many genetic components have been adapted into in vivo biosensors of small molecules, which couple the intracellular concentrations of small molecules to easily detectable readouts such as fluorescence, absorbance, and cell growth. Such biosensors allow a high-throughput screening of the small-molecule products, and can be roughly classified as protein-based and RNA-based biosensors. This review summarizes the recent developments in the design and applications of biosensors for small-molecule products.