Mutant strains of Escherichia coli, a method of testing potential antibacterial agents using said strains as well as a testing kit

A method of testing chemical compounds for potential antibacterial activity, comprising

• producing a mutant of an Escherichia coli strain that possesses ΔKtrans deletions of the following potassium transporter genes:
• Kdp, Kup and Trk, measuring the growth of cultures of the resulting mutant Escherichia coli strain in the presence of the compound being tested and limiting potassium concentrations, wherein the growth of the Escherichia coli strain possessing the ΔKtrans deletions indicates the facilitation of potassium transport into the Escherichia coli cell by the tested compound, further comprising the following stages
• producing a mutant Escherichia coli strain possessing ΔKtrans deletions of the following potassium transporter genes:
• Kdp, Kup and Trk as well as additionally possessing the deletion ΔmscS and/or the deletion ΔmscL of at least one of the genes encoding mechanically gated channels selected from the group consisting of mscS and mscL, using the same initial Escherichia coli strain, and then measuring the growth of this mutant in the presence of the tested compound and limiting concentrations of potassium, wherein:
• the growth of a strain possessing ΔKtrans deletions and the growth of a strain possessing the deletions ΔKtrans, ΔmscS and ΔmscL indicates that the tested compound exhibits no activity towards the MscS and MscL channel proteins,
• the growth of strains possessing ΔKtrans deletions, and the failure to grow of strains possessing the deletions ΔKtrans, ΔmscS and ΔmscL indicates the effect of the tested substance on mechanically gated receptors,
• the growth of the strain possessing the deletions ΔKtrans and ΔmscL in the presence of the tested compound exhibiting an effect on the activity of mechanically gated channels indicates that the tested substance is a specific activator of the MscS channel,
• the growth of the strain possessing the deletions ΔKtrans and ΔmscS in the presence of the tested compound exhibiting an effect on the activity of mechanically gated channels means that the tested compound is a specific activator of the MscL channel.