15 ml polypropylene tubes

The stability of the two batches of magistral preparations containing phages EFgrKN and EFgrNG was determined by the double agar overlay method [15 (link)]. The preparations were stored in 15 mL polypropylene tubes (Greiner Bio-One, Vilvoorde, Belgium) at 4 °C. As noted earlier, only joint titers were defined.

Phage stocks were diluted to 10 mL, in triplicate in five different solutions to produce different starting concentrations, i.e., 9 and 7 log pfu/mL in 15 mL polypropylene tubes (GreinerBioOne, Vilvoorde, Belgium), and stored at 4 °C.
Five different solutions used were: 5% glucose infusion solution (Fresenius Kabi, Schelle, Belgium); 0.9% NaCl infusion solution (Fresenius Kabi, Schelle, Belgium); Hartmann infusion solution (Baxter, Lessines, Belgium); DPBS supplemented with (w/) Ca²⁺ and Mg²⁺ (Lonza Biosciences, Verviers, Belgium); and without (w/o) Ca²⁺ and Mg²⁺ (Lonza Biosciences, Verviers, Belgium). Table 2 summarizes the detailed composition and characteristics of the five storage solutions. Phage infectivity was tested by determination of phage titer with the double agar overlay method on propagating bacterial strains, as described previously [25 (link)].