Aim: The aim of this study was to determine the morphological diversity and environmental survival of human-specific phages infecting Enterococcus faecium host strain MW47, to support their use as microbial source tracking (MST) markers.
Methods and results: Twenty phages capable of infecting strain MW47 were propagated and their morphologies were determined using transmission electron microscopy (TEM), which revealed that a heterogeneous group of phages was able to infect strain MW47. Three distinct morphologies from two different families (Myoviridae and Siphoviridae) were observed. In situ inactivation experiments were subsequently conducted to determine their environmental persistence.
Conclusion: The findings revealed a statistically significant link between morphology and the rate of inactivation, with phages belonging to the Myoviridae family demonstrating more rapid inactivation in comparison to those belonging to the Siphoviridae family.
Significance and impact of study: The results suggest that while Enterococcus MW47 phages appear to be a potentially valuable MST tools, significant variations in the persistence of the different phages mean that the approach should be used with caution, as this may adversely affect the reliability of the approach, especially when comparing MW47 phage levels or the presence across different matrices (e.g. levels in sediments or shellfish). This highlights the importance of elucidating the ecological characteristics of newly proposed MST markers before they are used in full-scale MST investigations.
Keywords: Enterococcus; TEM; bacteriophages; diversity; inactivation; markers; microbial source tracking; viruses.
© 2018 The Society for Applied Microbiology.