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

MERCANTI, D.; ACKERMANN, H.-W.; QUIBERONI, A.

INTERVIROLOGY

KARGER

Lugar: Basel; Año: 2015 p. 49 - 56

0300-5526

Background/Aims: 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 Lactobacillus paracasei phages iLp84 and  iLp1308, infective for probiotic strains. Methods: 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. Results: Phages iLp84 and  iLp1308 belong to the Siphoviridae 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 iLp84, and 51 min, 92 min and 28 for iLp1308, respectively, at 37° C. A clear influence of temperature on phage kinetics was observed. Regarding EOP, iLp84 produced plaques on only 1 out of 8 strains tested. Conclusion: Noticeable differences in adsorption, kinetics and EOP were found for two morphologically identical temperate L. paracasei phages of similar origin.