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Phages C-2 and J: IncC and IncJ plasmid-dependent phages, respectively
Abstract:
Phages C-2 and J were isolated from sewage. Phage C-2 was filamentous and formed plaques on Salmonella typhimurium strains carrying various C plasmids. It also plated on Proteus mirabilis and Serratia marcescens strains carrying particular C plasmids, but failed to form plaques on lines of Escherichia coli K12 strains harbouring most of these plasmids, although in all cases, phage multiplication on the strains was demonstrated. No phage increase occurred in any strain which lacked a C plasmid or contained plasmids of other incompatibility groups. The phage was sensitive to chloroform and, unlike other filamentous bacterial viruses, adsorbed to shafts of conjugative pili. It had a disc-like structure at the end which attached to the pilus. Phage C-2 had a buoyant density of 1 . 30 g cm-3 and a single-stranded circular DNA genome of 3 . 0 MDal. Phage J had an hexagonal head with an inter-apical distance of 40 nm and a short noncontractile tail. It was resistant to chloroform and diethyl ether. The phage formed plaques or propagated on E. coli strains harbouring some IncC plasmids and all IncJ and IncD plasmids tested. The phage did not form plaques but propagated on P. mirabilis and Ser. marcescens strains carrying these plasmids. It did not plate or propagate on S. typhimurium strains harbouring the plasmids. The plaques were very hazy and variable in size. The phage attached sparsely, at a site which appeared to be located at the base of the tail, to sides of conjugative pili.
Insights
Two novel phages, C-2 and J, were isolated from sewage. Phage C-2 infects Salmonella strains with C plasmids, while Phage J targets E. coli strains with specific plasmids, revealing distinct host interactions.
Area of Science:
- Microbiology
- Virology
- Molecular Biology
Background:
- Bacteriophages (phages) are viruses that infect bacteria.
- Phages play crucial roles in bacterial evolution and ecology.
- Understanding phage-host interactions is vital for phage therapy and biotechnology.
Purpose of the Study:
- To isolate and characterize novel bacteriophages from sewage.
- To investigate the host range and infection mechanisms of isolated phages.
- To determine the physical and genetic properties of the phages.
Main Methods:
- Bacteriophage isolation and plaque assays.
- Electron microscopy for phage morphology.
- Buoyant density centrifugation and DNA analysis.
- Host range determination on various bacterial strains with specific plasmids.
Main Results:
- Phage C-2, a filamentous phage, infects Salmonella typhimurium strains carrying C plasmids and exhibits sensitivity to chloroform.
- Phage J, an icosahedral phage, infects E. coli strains with IncC, IncJ, and IncD plasmids, showing resistance to chloroform and diethyl ether.
- Both phages adsorb to conjugative pili, indicating a unique interaction mechanism.
Conclusions:
- Phages C-2 and J possess distinct host ranges and infection strategies.
- The interaction with conjugative pili is a common feature, suggesting a role in plasmid transfer or phage propagation.
- These findings contribute to the understanding of phage diversity and host specificity.