a) Plaques of phage KSL-1; b) and c) electron micrograph of phage KSL-1, phage KSL-1 were negatively stained with 2% (w/v) phosphotungstic acid. Magnification: 37,000 × and 135000×, respectively. DNA characterization The restriction patterns of phage KSL-1 (Figure 2) were obtained with restriction endonucleases (EcoR I, Hind III, BamH I, SnaB I, Sal I and Sac I). Like most tailed phage, the genome was found to be double-stranded DNA. The genome size was determined to be approximately 53 kb (lane 4) running it with

λHind III DNA marker and GeneRuler 1Kb DNA ladder on 0.8% agarose gel, which was different from Pseudomonas fluorescens phage φIBB-PF7A(42 kb) [15]. Although the genome size of the phage KSL-1 was similar to phage ΦGP100 (50 kb), the morphologies of these two phages had significant difference [16]. Figure 2 Agarose gel electrophoresis showing restriction fragments LDC000067 cost generated from digesting phage KSL-1 DNA with endonuclease. Lanes are as follows: M1,Takara λHind III DNA Marker; M2, GeneRuler 1Kb DNA Ladder; 0, undigested; 1, EcoR I; 2, Hind III; 3, BamH I; 4, SnaB I; 5, Sal I; 6, Sac I. Optimal multiplicity of infection (MOI) of KSL-1 The MOI

resulting in the highest phage titer was considered to be optimal for the following CBL0137 manufacturer experiments [17]. In the present study, the optimal MOI of phage KSL-1 was determined to be 0.001, i.e., KSL-1 lysate of about 10 × 1011/mL would be obtained (Figure 3). Figure 3 Optimal multiplicity of infection (MOI) of phage KSL-1. Comparison of phage titer after incubation for 3.5 h at six ratios of MIO (0.00001, 0.0001, 0.001, 0.01, 0.1 and 1 PFU/CFU) in LB medium. One-step growth curve The one-step growth curve experiment of KSL-1 was performed for determining the latent time period and burst size of phage. There is a progressive relationship between burst size and latent period such that an optimal latent period leads to high phage fitness, an upsurge in burst size may contribute to plaque size or larger plaques with higher burst size [18, 19]. Burst size is calculated as the ratio of the final count of liberated phage particles

to the initial count of infected bacterial cells during the latent period [20]. Burst size and latent period are influenced by host, medium compositions and incubation temperature and specific growth Sulfite dehydrogenase rate [21]. From Figure 4, the latent period was calculated to be 90 min. the burst time was 75 min and the calculated burst size was about 52 phage particles per infected cell. Figure 4 One-step growth curve of phage KSL-1. Factors affecting phage KSL-1 stability As shown in Figure 5, after 60 min incubation the phage titers decreased from the initial incubated level of 9.5 log PFU/mL to about 8.8 log PFU/mL, 8.9 log PFU/mL and 8.9 log PFU/mL at pH 4.0, 5.0 and 6.0, Pevonedistat purchase respectively, while a sharp decrease appeared to be about 8.5 log PFU/ml when pH value was set as 11.0. Scarcely any reduction of the phage titer was observed at other pH values (7.0, 8.0, 9.0 and 10.0).