ABSTRACT
OBJECTIVE To characterize bacteriophage isolated from sewage with indicator of Klebsiella pneumoniae subsp pneumoniae.METHODS Bacteriophage was isolated from sewage by double-layer agar plate method,identified lytic or lysogenic capacity by induced methods of ultraviolet ray and mitomycin C,performed one-step growth experiments,decided the optimal multiplicity of infection,and its structure was observed with electron microscope.RESULTS The study found a strain of bacteriophage against the K.pneumoniae subsp pneumoniae.The phage had a head of 180 nm in diameter and a tail of 210 nm in length.The plaque was transparent and 4-7 mm in diameter.the optimal multiplicity of infection was 4,latent period was 35 min and burst period was 40 min,the average burst size was about 94 PFU/cell.CONCLUSIONS The isolated bacteriophage belongs to Stylovinidae,and it is a lytic bacteriophage with narrow host spectrum.Moreover,it is only sensitive to a part of K.pneumoniae subsp pneumoniae and a few of Escherichia coli strains.
ABSTRACT
Objective To identify some basic biological properties,optimal multiplicity of infection(MOI),one-step growth kinetics,serum neutralization rate constant of Pseudomonas aeruginosa phage PaP3 were determined, respectively. Methods The host bacteria were infected with PaP3 at six different MOI(0.0001,0.001,0.01,0.1,1 and 10,then lysated adequately, the phage titer of supernatant was determined.For one-step growth experiments,the host bacteria were infected with PaP3 at MOI=10, following centrifugation after 15 min adsorption,the pellet containing (partially) infected cells was resuspended in 3 ml of pre-warmed LB broth and incubated with 160rpm at 37℃.Samples(50?l) were taken at 10 min-intervals and immediately tittered by the double-layer agar plate method. A rabbit was immunized with purified PaP3 to prepare anti-PaP3 serum, reaction constants between antiserum and PaP1, PaP2, PaP3 were determined using cross neutralization test. Results 0.001 MOI-infected host bacteria gave the highest phage offsprings. One-step growth curve was determined according to the results of one-step growth experiments.Reaction constant was determined using neutralization test. Conclusion The optimal MOI of PaP3 was determined to be 0.001. One-step growth curve for PaP3 shows that the latent period is about 20 min, the rise period is 60 min, and the average burst size is about 31pfu/cell. Rate constant of reaction between antiserum and PaP3 is 262.