In this study, an allosteric transcription factors (aTFs) based biosensor for HMA is developed via directed evolution to realize the purpose of visualization of product yield and adaptive evolution. Our team found an allosteric transcription factor, PobR to conduct following experiment.

A PobR random library was built. Two reporter genes were used to screen for variants which can respond to HMA. By characterizing the screened biosensor from various aspects, the impact of mutations on biosensor response can be discussed from the perspective of amino acid replacement by computer simulation.

On the basis of this biosensor, obtaining high-yield HMA strains through adaptive laboratory evolution (ALE) methods is expected in order to screen out engineered bacteria with high HMA production. Additionally, directed evolution of Hmas enzyme which can produce HMA and mandelic acid (MA) can be studied in the future.