Differential bacteriophage mortality on exposure to copper

Area of Science:

• Microbiology
• Virology
• Materials Science

Background:

• Copper is known for its antimicrobial properties against various microbes, including viruses.
• Bacteriophages, viruses that infect bacteria, are diverse in structure and genetic material.
• Understanding copper's efficacy against different bacteriophage types is crucial for disinfection applications.

Purpose of the Study:

• To determine the inactivation rates of copper against a broad spectrum of bacteriophages.
• To investigate the influence of bacteriophage structure and lipid content on copper susceptibility.
• To explore the role of water in copper-mediated bacteriophage inactivation.

Main Methods:

• Two methods were employed: exposure of bacteriophage lysates to copper coupons and direct addition of copper sulfate to lysates.
• Bacteriophage survival was assessed by serial dilution and plating on bacterial hosts.
• Copper sulfate was added to a final concentration of 5 mM in lysate experiments.

Main Results:

• Significant inactivation was observed for double-stranded RNA (dsRNA) bacteriophages (Φ6, Φ8), single-stranded RNA (ssRNA) bacteriophage (PP7), single-stranded DNA (ssDNA) bacteriophage (ΦX174), and double-stranded DNA (dsDNA) bacteriophage (PM2).
• dsDNA bacteriophages PRD1, T4, and λ showed relative resistance to copper.
• Lipid-containing bacteriophages exhibited the highest susceptibility to copper toxicity.
• Copper's inactivation effect on bacteriophage Φ6 diminished as lysates dried, indicating a water-dependent mechanism.

Conclusions:

• Copper exhibits broad-spectrum inactivation of bacteriophages, with notable efficacy against lipid-containing types.
• The presence of water is essential for copper's virucidal activity against bacteriophages.
• These findings support the use of copper in strategies for controlling bacteriophage contamination.