A robust fluorescent glycerol kinase biosensor for reliable quantification of glycerol

Glycerol is a natural component of many biological samples, beverages and foodstuffs making accurate quantification relevant to a wide variety of industries and applications. Here we present a simple, rapid, and reliable biosensor for quantification of glycerol in a variety of sample types including water, alcoholic beverages, balsamic vinegar, honey, syrup and artificial human urine. This system leverages GFP-tagged Escherichia coli glycerol kinase with differential scanning fluorimetry of GFP-tagged proteins for direct quantification of glycerol via binding-induced increases in thermal stability. The GFP tag enables additional indication of potential matrix effects. The biosensor has a broad linear range of 31 μM - 7.5 mM and a limit of detection of 19 μM. Good agreement was obtained between the fluorescent glycerol kinase biosensor and a commercial glycerol quantification kit with glycerol-spiked artificial urine as well as a variety of alcoholic beverages and foodstuffs.