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Published on: December 23, 2022
Characterization of the Escherichia coli Virulent Myophage ST32
Honghui Liu1,2, Hany Geagea3, Geneviève M Rousseau4
1College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China. honghuiliu@hotmail.com.
Abstract:
The virulent phage ST32 that infects the Escherichiacoli strain ST130 was isolated from a wastewater sample in China and analyzed. Morphological observations showed that phage ST32 belongs to the Myoviridae family, as it has an icosahedral capsid and long contractile tail. Host range analysis showed that it exhibits a broad range of hosts including non-pathogenic and pathogenic E. coli strains. Interestingly, phage ST32 had a much larger burst size when amplified at 20 °C as compared to 30 °C or 37 °C. Its double-stranded DNA genome was sequenced and found to contain 53,092 bp with a GC content of 44.14%. Seventy-nine open reading frames (ORFs) were identified and annotated as well as a tRNA-Arg. Only nineteen ORFs were assigned putative functions. A phylogenetic tree using the large terminase subunit revealed a close relatedness with four unclassified Myoviridae phages. A comparative genomic analysis of these phages showed that the Enterobacteria phage phiEcoM-GJ1 is the closest relative to ST32 and shares the same new branch in the phylogenetic tree. Still, these two phages share only 47 of 79 ORFs with more than 90% identity. Phage ST32 has unique characteristics that make it a potential biological control agent under specific conditions.
Insights
A virulent phage, ST32, infecting Escherichia coli was isolated and characterized. This phage shows potential as a biological control agent due to its broad host range and unique genomic features.
Area of Science:
- Microbiology
- Virology
- Genomics
Background:
- Bacteriophages are viruses that infect bacteria and are increasingly explored for biocontrol.
- Escherichia coli (E. coli) is a common bacterium with both pathogenic and non-pathogenic strains.
Purpose of the Study:
- To isolate and characterize a novel virulent phage, ST32, targeting the E. coli ST130 strain.
- To analyze the morphological, host range, and genomic properties of phage ST32.
Main Methods:
- Isolation from wastewater, electron microscopy for morphology, host range assays.
- Genome sequencing, open reading frame (ORF) identification and annotation.
- Phylogenetic analysis using the large terminase subunit.
Main Results:
- Phage ST32 (Myoviridae family) possesses an icosahedral capsid and contractile tail, infecting a broad range of E. coli strains.
- Optimal amplification at 20 °C, with a genome size of 53,092 bp containing 79 ORFs.
- Phylogenetic analysis indicated close relation to unclassified Myoviridae phages, with Enterobacteria phage phiEcoM-GJ1 as the closest relative.
Conclusions:
- Phage ST32 exhibits unique characteristics, including a broad host spectrum and distinct genomic features.
- Its specific growth conditions and genetic makeup suggest potential as a biological control agent for E. coli.
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