Isolation, characterization and complete genome sequence of PhaxI: a phage of Escherichia coli O157 : H7

Salehe Sabouri Shahrbabak, Zahra Khodabandehlou, Ahmad Reza Shahverdi, Mikael Skurnik, Hans-Wolfgang Ackermann, Markku Varjosalo, Mojtaba Tabatabaei Yazdi, Zargham Sepehrizadeh

¹Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, PO Box 14155-6451, Tehran, Iran

²Pharmaceutics Research Center, Kerman University of Medical Sciences, PO Box 76175-493, Kerman, Iran

³Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki and Helsinki University Central Hospital Laboratory, Helsinki, Finland

⁴Department of Microbiology, Immunology, and Infectiology, Faculty of Medicine, Laval University, Quebec, QC; G1X 4C6, Canada

⁵Institute of Biotechnology, PO Box 65, University of Helsinki, Helsinki, Finland

Correspondence
Zargham Sepehrizadeh zsepehri{at}tums.ac.ir

Abstract

Bacteriophages are considered as promising biological agents for the control of infectious diseases. Sequencing of their genomes can ascertain the absence of antibiotic resistance, toxin or virulence genes. The anti-O157 : H7 coliphage, PhaxI, was isolated from a sewage sample in Iran. Morphological studies by transmission electron microscopy showed that it has an icosahedral capsid of 85–86 nm and a contractile tail of 115×15 nm. PhaxI contains dsDNA composed of 156 628 nt with a G+C content of 44.5 mol% that encodes 209 putative proteins. In MS analysis of phage particles, 92 structural proteins were identified. PhaxI lyses Escherichia coli O157 : H7 in Luria-Bertani medium and milk, has an eclipse period of 20 min and a latent period of 40 min, and has a burst size of about 420 particles per cell. PhaxI is a member of the genus ‘Viunalikevirus’ of the family Myoviridae and is specific for E. coli O157 : H7.