Abstract

Parichat Phumkhachorn and Pongsak Rattanachaikunsopon*

A bacteriophage infecting Vibrio harveyi was isolated from shrimp pond water, it was designated PW2. It infected all strains of V. harveyi but not other bacteria used in this study. The phage adsorption rate increased rapidly in the first 15 min of infection to 80% and continued to increase to 90% within 30 min of infection. The stability of phage PW2 was dependent on temperature and pH. It was inactivated by heating at 90°C for 30 min and by treating at pH 2, 3, 11and 12. From its one step growth curve, latent and burst periods were 30 and 120 min, respectively with a burst size of about 78 plaque-forming unit (pfu) per infected center. As analyzed by transmission electron microscopy, phage PW2 had an icosahedral head (50 ± 3.8 nm in diameter) with a noncontractile tail of 136 ± 6.2 nm long and 11 ± 0.5 nm wide and belongs to the Siphoviridae family. Six structural proteins (75, 60, 35, 30, 20 and 15 kDa) were detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis, its genome was found to be double stranded DNA with an approximate size of 46 kb.