Utilization of the ComRS system for the rapid markerless deletion of chromosomal genes in Streptococcus suis

To develop a markerless gene deletion strategy in Streptococcus suis to solve the problem that several serotypes against electrotransformation of foreign DNA. Bioinformatics retrieval was performed to identified ComRS systems functioning for natural transformation. A sacB-spc cassette with the upper and lower homologous fragments was amplification by fusion-PCR for spectinomycin-positive and sucrose-negative selection during gene deletion. Three phylogenetic clusters of ComR were identified to function for natural transformation by specific recognition to competence pheromone in S. suis. Thus, they were employed to establish gene deletion method. Its efficiency for genetic replacement was dependent on the length of homologs fragment and the concentration of donor DNA. This rapid gene-editing technique may greatly facilitate molecular studies on S. suis.