Fig. 1

P1 J72114 phagemid as a delivery tool for transduction of a foreign genetic cassette into Gram-negative Enterobacteriaceae. (a) Schematic diagram of P1-J72114 phagemid, characterized by constitutive expression of gfp placed under the BBa_J23115 promoter. The phagemid contains the chloramphenicol acetyltransferase gene (cat), which confers a chloramphenicol-resistant phenotype to transduced or transformed cells. Transduced E. coli cells will retain the J72114-gfp phagemid, giving constitutive gfp expression. (b) Representative image showing the presence of GFP-positive E. coli NCM3722 cells after transduction with serially diluted phagemid lysates delivering the gfp expression cassette. Serial dilutions of recovered cells (10¹, 10², 10³, and 10⁴) were made and spotted onto LB agar supplemented with chloramphenicol. (c) Quantification of transducing units (phage particles containing phagemid sequences) in various lab strains of E. coli. Each data point represents a biological replicate and is the average of four technical repeats. Horizontal lines represent the group mean. The p-values were determined and adjusted by the Kruskal–Wallis test and Dunn’s multiple comparison tests, respectively, and significance was defined as p < 0.05. * represents p < 0.05, while ** represents p < 0.005, for comparisons between BL21 vs NCM3722 and TOP10 vs MC1061 and phagemid transductants, respectively.