Phage Folac: an Folac plasmid-dependent bacteriophage.

Area of Science:

• Microbiology
• Virology
• Molecular Biology

Background:

• Plasmids, such as EDP208, a derivative of F-olac, confer specific traits to bacteria, including pilus production.
• Bacteriophages (phages) are viruses that infect bacteria and can be highly specific in their host range.
• Developing specific phages is crucial for diagnostics and understanding bacterial-plasmid interactions.

Purpose of the Study:

• To isolate and characterize a bacteriophage specific for bacterial strains harboring the EDP208 plasmid.
• To investigate the adsorption and multiplication characteristics of the isolated phage.
• To determine the phage's potential utility in distinguishing between plasmid-carrying and non-plasmid-carrying bacteria.

Main Methods:

• Enrichment of sewage with specific bacterial strains (Escherichia coli, Salmonella typhimurium) carrying the EDP208 plasmid.
• Isolation and characterization of bacteriophages based on their plating efficiency on target and non-target strains.
• Electron microscopy to determine phage morphology.
• RNA analysis and chloroform resistance tests.
• Phage multiplication assays on various bacterial strains with different plasmids.

Main Results:

• A specific phage, named F-olac, was isolated, plating only on strains with the EDP208 plasmid.
• F-olac has a hexagonal outline (28 nm diameter), contains RNA, is chloroform-resistant, and likely adsorbs to EDP208 pili near the tip.
• Phage multiplication occurred on E. coli/S. typhimurium with F-olac plasmid but not with other F complex plasmids; results with R71/TP224-Tc were inconclusive.
• F-olac is serologically related to phage UA-6, another EDP208-specific isolate.

Conclusions:

• The isolated phage F-olac demonstrates high specificity for bacteria harboring the EDP208 plasmid.
• F-olac's characteristics suggest a specific interaction mechanism with bacterial pili.
• This phage represents a valuable tool for research involving EDP208-carrying bacteria and potentially for diagnostic applications.