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Characterization of phage phi O139, a Vibrio cholerae O139 temperate bacteriophage with cohesive DNA termini
S Pajni1, N R Chowdhury, A Ghosh
1Institute of Microbial Technology, Chandigarh, India.
Abstract:
A temperate bacteriophage isolated from Vibrio cholerae O139, the new epidemic strain of cholera, was found to have a polyhedral head 65 nm in diameter and a rigid contractile tail 120 nm in length. The phage chromosome was a double-stranded DNA of 35 kb, with unique cohesive ends and had a G + C content of 58.8%. A restriction map of the phage DNA was constructed using the restriction endonucleases AvaI and BstEII. The phage, whose presence could be detected in nine out of 13 V. cholerae O139 isolates tested, was found to have identical chromosomal integration sites in all the strains. The phage attachment site (attP) was found to be located very close to one end of the genome.
Insights
A temperate bacteriophage infecting Vibrio cholerae O139 was characterized, revealing its DNA structure and integration sites. This phage is present in most tested O139 strains, suggesting a role in cholera epidemiology.
Area of Science:
- Microbiology
- Virology
- Genetics
Background:
- Vibrio cholerae O139 is a significant epidemic strain of cholera.
- Temperate bacteriophages can influence bacterial pathogenicity and evolution.
Purpose of the Study:
- To characterize a temperate bacteriophage isolated from V. cholerae O139.
- To investigate the phage's genetic material and integration mechanism.
Main Methods:
- Morphological characterization of the bacteriophage.
- DNA extraction, sequencing, and restriction mapping.
- Analysis of phage integration sites in V. cholerae O139 isolates.
Main Results:
- The bacteriophage possesses a polyhedral head (65 nm) and a contractile tail (120 nm).
- Its genome is a 35 kb double-stranded DNA with a G+C content of 58.8%.
- Identical chromosomal integration sites were found in 9/13 V. cholerae O139 isolates, with the attachment site (attP) near one genome end.
Conclusions:
- This temperate bacteriophage is prevalent in V. cholerae O139 strains.
- The phage's genetic features and conserved integration sites suggest a potential role in the epidemiology of O139 cholera.