Characterization of the morphology and genome of an Escherichia coli podovirus.

Escherichia coli is an important opportunistic pathogen. It can cause sepsis and severe infection. The application of lytic bacteriophages to treat infectious diseases is an alternative to antibiotics. A lytic Escherichia coli phage, designated IME-EC2, was isolated from hospital sewage. Transmission electron microscopy revealed that IME-EC2 to be a member of the family Podoviridae. It had a 60-nm head and a 15-nm tail. Here, we present the complete genome sequence of this phage, which consists of 41,510 bp with an overall G+C content of 59.2 %. A total of 60 coding sequences (CDS) were identified, and the phage genome does not contain any tRNA genes. Forty percent of the unknown CDSs are unique to IME-EC2. This phage does not show significant similarity to other phages at the DNA level, which suggests that IME-EC2 could be a novel phage. One of the unique features identified in the IME-EC2 genome was a gene coding for a putative colanic-acid-degrading protein, which could allow the phage to degrade bacterial capsule and biofilms. Another unique feature is that IME-EC2 does not contain a terminase small subunit, which suggests that this phage may have a unique packaging mechanism. The present work provides novel information on phages and shows that this lytic phage or its products could be exploited to destroy bacterial biofilms and pathogenic E. coli.