In Vitro and In Vivo Validation of ligA and tarI as Essential Targets in Staphylococcus aureus

A conditional expression system has been developed using the isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible Pspac promoter to validate essential genes of Staphylococcus aureus in vivo. The system has been applied to prove the essentiality of ligA and to evaluate the function of tarI, which was found to be essential in vitro but not in vivo.