Human-specific phages infecting Enterococcus host strain MW47: are they reliable microbial source tracking markers?

Area of Science:

• Microbiology
• Environmental Science
• Molecular Biology

Background:

• Enterococcus faecium is an important indicator species in environmental microbiology.
• Bacteriophages are viruses that infect bacteria and can serve as potential microbial source tracking (MST) markers.
• Human-specific phages offer a promising avenue for identifying sources of fecal contamination.

Purpose of the Study:

• To investigate the morphological diversity of human-specific phages targeting Enterococcus faecium strain MW47.
• To assess the environmental survival and persistence of these phages.
• To evaluate their suitability as microbial source tracking (MST) tools.

Main Methods:

• Propagation and isolation of twenty phages infecting Enterococcus faecium MW47.
• Morphological characterization using transmission electron microscopy (TEM).
• In situ inactivation experiments to determine phage environmental persistence.

Main Results:

• A heterogeneous group of phages infecting MW47 was identified, with three distinct morphologies from the Myoviridae and Siphoviridae families observed.
• Phages exhibited varied rates of environmental inactivation.
• A statistically significant correlation was found between phage morphology and inactivation rate.

Conclusions:

• Myoviridae phages showed more rapid inactivation than Siphoviridae phages.
• Enterococcus faecium MW47 phages are potentially valuable MST tools, but their varied persistence necessitates cautious application.
• Further elucidation of ecological characteristics is crucial before widespread use of these phages as MST markers.