RESUMEN
Serratia marcescens jn01 was employed as the host for the isolation of phages from environmental sewage. One strain of phage named SmPjn was purified by picking transparent plaque with 2mm diameter and clear edge on the double-layer agar repeatedly. Electron micrographs indicated that the phage head was icosahedral with head size and tail length of (58 +/- 2.16) x (55 +/- 0.47) nm and (7 +/- 1.25) nm, respectively. On the basis of the morphology, this phage belongs to the family Podoviridae. Host-range determination revealed that the phage was capable of infecting the other two isolates of S. marcescens, P25 and CMCC41002. The optimal multiplicity of infection was 1. A one-step growth curve of SmPjn indicated that the latent period and burst size were estimated at 50 min and 1,125 pfu/cell, respectively . Genomic DNA of SmPjn was above 27kb in size and could be digested by Hind Ill and EcoR I into 11 and 9 visible fragments after electrophoresis, respectively. A novel Podoviridae-phage infecting S. marcescens was firstly reported in China.