Fig. 1. Phage infectivity of M. smegmatis and Mtb H37Rv in solid agar plates, and in Mtb liquid culture.

Serial dilutions (10²–10⁴ pfu) of different strains of bacteriophages were mixed with 1 × 10⁵ CFUs M. smegmatis (A) or H37Rv (B) in 7H9 medium and incubated at 37 °C with shaking for 1 h. The infection cultures were then mixed with 0.8% top agar and spread on 12-well 7H10 agar plates supplemented with 10% OADC enrichment. C–F: H37Rv (1 × 10⁵ CFUs) were infected with various bacteriophages at an MOI of 1 for 1 h, then inoculated into 20 mL 7H9 media supplemented with 10% ADC and incubated at 37 °C for 9 days. The cultures were sampled at days 3, 6, and 9 post infection by plating 10 μL of 10-fold serial dilutions of on the 7H10 agar plates and cultured at 37 °C for CFU determination. C: OD₆₀₀ of sampled liquid cultures was measured at different time points as indicated. D: Statistics of the CFUs of each sampled liquid culture sampled at various time points. E: Titering assay of phage-Mtb liquid culture sampled at different time points. The data are representative results of two independent experiments. F: Phage infection of H37Rv that expresses a GFP reporter gene. An MOI of 1 was used to infect H37Rv-GFP. GFP expression was pictured under fluorescence microscopy after nine days of phage infection.