The phage delivered CRISPR/Cas9 was applied to eliminate resistance plasmids. Plasmids with or without the target site were treated with the modified vB_Cas9 phage or the wild-type temperate phage (WT) at a MOI of ~20 for 8 h. (A) Data represent the colony counts of resistance plasmid-possessing bacteria following different phage treatment (n = 3, mean ± SD). (B) Time-course analysis of the MG1655 pUCtargetk strain treated with vB_Cas9 or the wild-type control. The relative fold change of pUCtargetk copy number was determined at various time points using qPCR (n = 3, mean ± SD). (C) Kanamycin-resistant strains containing the targeted plasmid were cultured with vB_Cas9 or the wild-type control at various MOIs for 8 h. Surviving bacterial cells were determined by colony counts (n = 3, mean ± SD). (D) MG1655 pUCtargetk cells was treated with combined use of modified phage and kanamycin, lytic vB_253 phage or wild-type vB_365 control. The concentration of plasmid in the bacterial supernatant was quantified by qPCR (n = 3, mean ± SD).