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Updated: Apr 18, 2026

Author Spotlight: An Adapted Optical Density-Based Microplate Assay for Characterizing Actinobacteriophage Infection
Published on: June 30, 2023
Characterization of two temperate Lactobacillus paracasei bacteriophages: morphology, kinetics and adsorption
Diego J Mercanti1, Hans-Wolfgang Ackermann, Andrea Quiberoni
1Instituto de Lactología Industrial, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina.
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 Φ iLp84 and Φ 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 Φ iLp84 and Φ 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 Φ iLp84, and 51 min, 92 min and 28 for Φ iLp1308, respectively, at 37°C. A clear influence of temperature on phage kinetics was observed. Regarding EOP, Φ 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.
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