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