Development of versatile procedure based on natural transformation for marker-free targeted genetic modification in Streptococcus thermophilus

A versatile natural transformation protocol was used as a tool to develop marker-free procedure for site-directed genetic modification in Streptococcus thermophilus strains. The developed natural transformation protocol combined with a powerful positive screen could be successfully applied for the construction of recombinant strains in one step without using any antibiotic resistance marker.