Development of an Haa1-Based Biosensor for Acetic Acid Sensing in Saccharomyces cerevisiae.

Transcription factor (TF)-based biosensors are important tools in strain development and screening as they can allow accurate monitoring of intracellular concentrations of a molecule. Acetic acid is one of the main inhibitors in lignocellulosic biomass and a major challenge when using yeast cell factories for biorefinery applications. Thus, developing acetic acid tolerant strains is of great importance. The acetic acid sensing biosensor developed relies on the endogenous Saccharomyces cerevisiae TF Haa1 that upon binding of acetic acid translocates to the nucleus. The acetic acid biosensor can be used as a tool for strain development and evaluation, as well as for screening of acetic acid-producing strains and for dynamic monitoring of acetic acid accumulation. This chapter describes a methodology for developing a TF-based biosensor for acetic acid sensing. Protocols for design considerations, part construction, and characterization procedures are included. The approach can potentially be adapted to any molecule where a suitable TF can be identified.