SCT and infection: The pspA promoter was chosen to create the biosensor because pspA gene is known to be induced under various stress conditions, such as heat shock, infection by filamentous phages (production of secretin encoded by the phage, a protein forming pores in the outer membrane), inhibition of lipid biosynthesis and addition of proton ionophores, as well as the PspA protein (phage shock protein A) plays a key role in protecting the cell membrane from damage [31,43].