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Physiological, morphological, and physicochemical characterization of a novel Escherichia coli bacteriophage, phage
M Müller1, M Wurtz, E Kellenberger
1M. E. Müller-Institute for High-Resolution Electron Microscopy, Biocenter, University of Basel, Switzerland.
Abstract:
A double-stranded DNA containing, T even-like, Escherichia coli bacteriophage, called MM, has been isolated from the local sewage and purified by polyethylene glycol precipitation followed by banding on a cesium chloride three-step gradient. It yields a burst size of 75 particles per infected cell, and has an adsorption coefficient of 3.3 x 10(-10) cm3/min and a latent period of 45 min. Electron microscopy of phage MM reveals an isometric icosahedral head, 92 nm long and 81 nm wide, and a 112-nm-long contractile tail with six pairs of 40-nm-long fibers attached to its baseplate. Phage MM appears similar to E. coli phage T4 or Salmonella phage O1. The density of phage MM in cesium chloride is 1.515 g/ml, and its total mass is 144 MDa. Gel electrophoresis of purified MM capsids displays two major capsid proteins in approximately equimolar amounts and with apparent molecular masses of 38 and 15 kDa. Similarly, purified MM tails yield two major polypeptides with apparent molecular masses of 55 and 16 kDa, most likely representing the major tail sheath and tail tube polypeptides. Its double-stranded DNA has a G-C content of 50%, a length of 131 kilobases (kb), and a mass of 89 MDa.
Insights
A novel double-stranded DNA bacteriophage, named MM, was isolated from sewage. This T even-like Escherichia coli phage exhibits unique structural and genomic properties, offering insights into phage biology.
Area of Science:
- Microbiology
- Virology
- Molecular Biology
Background:
- Bacteriophages are viruses that infect bacteria.
- Escherichia coli bacteriophages are widely studied due to their relevance in various biological processes.
- Characterization of novel phages is crucial for understanding phage diversity and potential applications.
Purpose of the Study:
- To isolate and characterize a novel double-stranded DNA bacteriophage from sewage.
- To determine the physical, morphological, and genomic properties of the isolated phage, designated MM.
- To compare phage MM with known bacteriophages like E. coli phage T4.
Main Methods:
- Isolation from sewage using polyethylene glycol precipitation.
- Purification via cesium chloride density gradient centrifugation.
- Characterization using electron microscopy, gel electrophoresis, and DNA analysis.
Main Results:
- Phage MM is a T even-like Escherichia coli bacteriophage with a burst size of 75, adsorption coefficient of 3.3 x 10(-10) cm3/min, and latent period of 45 min.
- Electron microscopy revealed an isometric icosahedral head (92x81 nm) and a contractile tail (112 nm) with fibers.
- SDS-PAGE identified major capsid proteins (38 and 15 kDa) and tail proteins (55 and 16 kDa). The double-stranded DNA is 131 kb with 50% G-C content.
Conclusions:
- Phage MM possesses distinct morphological and genomic characteristics.
- Its structural similarity to T4 suggests potential evolutionary relationships.
- This study contributes to the characterization of novel bacteriophages and their genetic material.