Genetic modification of intractable staphylococcal clones by heat-shock facilitated phage transduction

Increasing recognition of commensal bacteria as a requirement for microbiome integrity and pathogen exclusion puts urgency to the molecular characterization of commensal interactions. However, many commensals cannot be transformed with available methodology because of potent restriction barriers. We developed a new method for the introduction of plasmid DNA into otherwise intractable non- Staphylococcus aureus (NAS) staphylococci, important commensal members of human nose and skin microbiomes, by phage transduction. We demonstrate that a precise pulse of recipient bacteria with elevated temperatures prior to exposure to transducing phages renders NAS isolates effectively and transiently amenable to transduction. Transduction of NAS mutants lacking restriction-modification (RM) systems did not profit from a heat shock indicating that it is the transient deactivation of RM enzymes that permit transduction. Our method also facilitated the transduction of other Bacillota from the genera Bacillus and Listeria indicating that it will support research on different bacterial groups from diverse ecosystems.