Supplementary Material for: Characterization of Two Temperate Lactobacillus paracasei Bacteriophages: Morphology, Kinetics and Adsorption

<b><i>Background/Aims:</i></b> Adsorption and kinetic parameters, latent period, burst size and burst time, are characteristics of phage/host systems and can be affected by several environmental factors. As only few studies have focused on temperate dairy phages, we characterized these parameters on temperate <i>Lactobacillus paracasei</i> phages Φ i<i>Lp</i>84 and Φ i<i>Lp</i>1308, infective for probiotic strains. <b><i>Methods:</i></b> Phages were characterized by transmission electron microscopy and genomic DNA restriction. Adsorption under different environmental conditions, phage kinetics and efficiency of plating (EOP) were determined using the double-layer titration method. <b><i>Results:</i></b> Phages Φ i<i>Lp</i>84 and Φ i<i>Lp</i>1308 belong to the <i>Siphoviridae</i> family and have genome sizes of 38 and 34 kbp, respectively. Adsorption was affected by calcium concentration, pH, temperature and host viability, and reached a limit at very high multiplicity of infection. Latency, burst time and burst size were of 85 min, 131 min and 46 for Φ i<i>Lp</i>84, and 51 min, 92 min and 28 for Φ i<i>Lp</i>1308, respectively, at 37°C. A clear influence of temperature on phage kinetics was observed. Regarding EOP, Φ i<i>Lp</i>84 produced plaques on only 1 out of 8 strains tested. <b><i>Conclusion:</i></b> Noticeable differences in adsorption, kinetics and EOP were found for two morphologically identical temperate <i>L. paracasei</i> phages of similar origin.