Lysogenic conversion for multiple characters in a strain of Staphylococcus aureus.

Area of Science:

• Microbiology
• Bacteriology
• Virology

Background:

• Staphylococcus aureus is a significant human pathogen.
• Bacteriophages can infect and alter bacterial hosts.
• Lysogenic conversion is a process where bacteriophages change bacterial characteristics.

Purpose of the Study:

• To investigate lysogenic conversion in Staphylococcus aureus using bacteriophages LS1 and LS2.
• To characterize the phenotypic and cell wall changes in lysogenized S. aureus strains.
• To confirm the role of bacteriophages in inducing stable genetic modifications.

Main Methods:

• Lysogenization of nonlysogenic S. aureus strains with bacteriophages LS1 and LS2.
• Infection via protoplast inoculation or co-inoculation with virulent phages.
• Phenotypic characterization including enzyme activity, phage typing, fermentation, and cell wall composition analysis.
• Electron microscopy to confirm phage liberation.

Main Results:

• Lysogenized S. aureus strains showed significant phenotypic changes: coagulase, deoxyribonuclease, and lipase negative; untypable by standard phages; altered mannitol fermentation and glucose fermentation products (l-(+)-lactic acid only).
• Cell walls of lysogenized strains had reduced glycine and increased serine content, and lacked protein A.
• Antigenic factors and ribitol in cell wall teichoic acid indicated a parental relationship.
• Lysogenic phages were excluded by superinfecting phages, and revertant strains regained original characteristics.

Conclusions:

• The observed changes were attributed to lysogenic conversion, a stable modification of S. aureus by bacteriophages LS1 and LS2.
• Lysogenic conversion significantly alters bacterial virulence factors and cell wall composition.
• The study provides evidence for bacteriophage-mediated genetic exchange influencing bacterial traits.