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Phage C-1: an IncC group; plasmid-specific phage
Abstract:
A phage was isolated from sewage and shown to form plaques on Salmonella typhimurium strains carrying C plasmids. It failed to multiply on strains lacking plasmids of this group. It also plated on Proteus mirabilis and Serratia marcescens strains carrying various IncC plasmids but failed to form plaques on Escherichia coli strains harbouring most of these plasmids, although in all cases, phage multiplication on the strains was demonstrated. No phage increase occurred in any of the strains which lacked an IncC plasmid or contained plasmids of other incompatibility groups. The phage is small, hexagonal in outline, contains RNA, is resistant to chloroform and adsorbs to the shafts of pili coded for by IncC plasmids.
Insights
A novel phage specifically targets bacteria with IncC plasmids, demonstrating its potential as a tool for studying these genetic elements. This phage requires IncC plasmids for plaque formation but can multiply in various bacterial hosts.
Area of Science:
- Microbiology
- Virology
- Bacteriology
Background:
- Bacteriophages are viruses that infect bacteria and can serve as valuable tools in molecular biology and medicine.
- IncC plasmids are a group of conjugative plasmids found in various Gram-negative bacteria, often carrying antibiotic resistance genes.
- Phage-host interactions are often specific and can be influenced by bacterial genetic elements like plasmids.
Purpose of the Study:
- To isolate and characterize a novel bacteriophage from sewage.
- To determine the host range and replication requirements of the isolated phage.
- To investigate the phage's interaction with bacteria carrying IncC plasmids.
Main Methods:
- Enrichment culture of sewage samples to isolate phages.
- Plaque assays on various bacterial strains (Salmonella typhimurium, Proteus mirabilis, Serratia marcescens, Escherichia coli) with and without IncC plasmids.
- Electron microscopy to determine phage morphology.
- Chloroform resistance assay.
- Adsorption assays to bacterial pili.
Main Results:
- A bacteriophage was isolated from sewage that forms plaques on Salmonella typhimurium strains carrying IncC plasmids.
- The phage failed to multiply on strains lacking IncC plasmids or those with other incompatibility groups.
- While plaque formation was limited in Escherichia coli, phage multiplication was demonstrated in various bacterial hosts carrying IncC plasmids.
- The phage is small, hexagonal, contains RNA, is chloroform-resistant, and adsorbs to pili encoded by IncC plasmids.
Conclusions:
- The isolated phage exhibits a specific requirement for IncC plasmids for plaque formation, suggesting a dependence on plasmid-encoded factors.
- The phage's ability to adsorb to pili coded by IncC plasmids indicates a potential mechanism for host recognition and entry.
- This phage represents a potential new tool for studying IncC plasmids and their associated bacterial hosts.