High‐throughput G protein‐coupled receptor‐based autocrine screening for secondary metabolite production in yeast

Biosensors are valuable tools in accelerating the test phase of the design‐build‐test‐learn cycle of cell factory development, as well as in bioprocess monitoring and control. G protein‐coupled receptor (GPCR)‐based biosensors enable cells to sense a wide array of molecules and environmental conditions in a specific manner. Due to the extracellular nature of their sensing, GPCR‐based biosensors require compartmentalization of distinct genotypes when screening production levels of a strain library to ensure that detected levels originate exclusively from the strain under assessment. Here, we explore the integration of production and sensing modalities into a single Saccharomyces cerevisiae strain and compartmentalization using three different methods: (1) cultivation in microtiter plates, (2) spatial separation on agar plates, and (3) encapsulation in water‐in‐oil‐in‐water double emulsion droplets, combined with analysis and sorting via a fluorescence‐activated cell sorting machine. Employing tryptamine and serotonin as proof‐of‐concept target molecules, we optimize biosensing conditions and demonstrate the ability of the autocrine screening method to enrich for high producers, showing the enrichment of a serotonin‐producing strain over a nonproducing strain. These findings illustrate a workflow that can be adapted to screening for a wide range of complex chemistry at high throughput using commercially available microfluidic systems. Construction of self‐sensing yeast equipped with a G protein‐coupled receptor‐based biosensor module and a bioproduction module facilitates a streamlined screening strategy to identify high‐producing variants. We demonstrate this approach in three formats by which to link genotype with extracellular production phenotype: (1) microtiter plates, (2) colony screening, and (3) encapsulation in double emulsion microdroplets combined with fluorescence‐activated cell sorting.