A key limitation to engineering microbes for advanced biofuel production is a reliance on low-throughput chromatography-based screens for chemical detection. While colorimetric chemicals are amenable to high-throughput screens, many value-added chemicals are not colorimetric and require sensors for high-throughput screening. Here, we present the use of G-protein coupled receptors (GPCRs) known to bind medium-chain fatty acids in mammalian cells to rapidly construct chemical sensors in yeast. Medium-chain fatty acids are immediate precursors to the advanced biofuel fatty acid methyl esters, which can serve as a “drop-in” replacement for D2 diesel. One of the sensors detects even-chain C8-C12 fatty acids with a 13- to 17-fold increase in signal after activation, with linear ranges up to 250μM. Introduction of a synthetic response unit alters both dynamic and linear range, improving the sensor response to decanoic acid to a 30-fold increase in signal after activation, with a linear range up to 500μM. To our knowledge, this is the first report of a medium-chain fatty acid biosensor, which we envision could be applied to the evolutionary engineering of fatty acid-producing microbes. Given the affinity of GPCRs for a wide range of chemicals, it should be possible to rapidly assemble new biosensors for advanced biofuels by simply swapping the GPCR sensing unit. These sensors should be amenable to a variety of applications that require different dynamic and linear ranges, by introducing different response units.

GPCR-based chemical biosensor for advanced biofuels

251st National Meeting (2016)

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