Phages of Lactobacillus casei/paracasei: response to environmental factors and interaction with collection and commercial strains

Abstract

Aim: To investigate the influence of several environmental factors on the viability and cell‐adsorption for two Lactobacillus casei/paracasei bacteriophages (PL‐1 and J‐1). Methods and Results: Both phages showed a remarkably high specificity of species, sharing similar host spectra. Two phages and four sensitive strains were used to conform five phage/strain systems. Each showed a particular behaviour (burst size: ranging from 32 to 160 PFU/infective centre; burst time: 120–240 min and latent time: 5–90 min). For both phages, the viability was not significantly affected from pH 4 to 11 (room temperature) and from pH 5 to 10 (37°C). Adsorption rates were not influenced by calcium ions, but decreased after the thermal inactivation of cells. Adsorption rates were high between 0 and 50°C with maximum values at 30°C and pH 6. System PL‐1/Lact. paracasei A showed noticeable differences in comparison with the others, being times required to reach 90% of adsorption of 4 h and lower than 45 min, respectively. Conclusions: The data obtained in this work demonstrated that environmental parameters can influence the viability and cell adsorption rates of Lact. casei/paracasei phages. The extent of this influence was phage dependent. Significance and Impact of the Study: This work contributes to the enlargement of the currently scarce knowledge of phages of probiotic bacteria.

Characterization of Two Virulent Phages of Lactobacillus plantarum

“…This low adsorption could be due to a limited number of phage receptors (in comparison with L. plantarum ATCC 8014) or their availability on the cell surface. Similar results were reported for Lactobacillus paracasei phages (8). Conversely, phage B2 was amplified on L. plantarum strain PLN and on its host ATCC 8014 (Table 1).…”

Characterization of Siphoviridae phage Z and studying its efficacy against multidrug-resistant Klebsiella pneumoniae planktonic cells and biofilm

“…Thermal stability tests for the phage were conducted according to the methodology described by Capra et al (2006), with some modifications. Phage suspensions (9.0610 5 c.f.u.…”

“…Experiments for testing pH stability were carried out as described by Capra et al (2006), with some modifications. We established a pH gradient ranging from 1 to 11 (pH 1, 3, 5, 7, 9, 11).…”

Efficacy of Bacteriophage Therapy in Experimental Sepsis and Meningitis Caused by a Clone O25b:H4-ST131 Escherichia coli Strain Producing CTX-M-15

“…pH stability and thermal stability tests were carried out as previously described (9,13). Briefly, suspensions of 10 9 PFU phage/ml in LB medium were incubated at different pH and temperatures, and samples were taken at intervals for assay of surviving PFU.…”