Staphylococcus species infected by a bacteriophage with a tail that is both curved and contractile

TL;DR

A new bacteriophage with a unique curved and contractile tail was found to infect multiple Staphylococcus species, including drug-resistant strains.

Contribution

Discovery of a novel phage with a morphologically distinct tail and broad host range across Staphylococcus species.

Findings

Phage JS1 infects seven non-aureus Staphylococcus species and clinical S. aureus strains, including methicillin-resistant isolates.

JS1 has a 252 nm long, curved, contractile tail with a 1/R curvature value of 7.6 ± 1.3 μm−1, distinct from known phage morphotypes.

JS1 encodes hydrolases, including JS1_0224, which etches the Staphylococcal cell wall.

Abstract

Using a selective plating strategy for staphylococci, we surveyed the local community wastewater and purified 16 independent isolates representing the following seven species of Staphylococcus: S. cohnii, S. equorum, S. lentus, S. nepalensis, S. sciuri, S. shinii, and S. xylosus. Staphylococcus aureus was not detected. The wastewater also served as a source to identify a bacteriophage (phage), referred to here as JS1, that could infect all these species of Staphylococcus, as well as a range of clinical S. aureus strains, including methicillin-resistant isolates. The class Caudoviricetes are tailed phages, and classification systems recognize the following three major morphotypes: the Myo-like (medium-to-long, straight, contractile tails), Sipho-like (long, flexible, non-contractile tails), and Podo-like (very short, rigid tails). Electron microscopy showed that JS1 virions have 252 nm long, curved, contractile tails. Curvature analysis showed that this represented a range with a 1/R value of 7.6 ± 1.3 μm−1, where R is the radius of curvature. Phage JS1 also encodes hydrolases that are assembled onto the phage virions. One of these hydrolases, JS1_0224, was biochemically characterized and found to etch regions from the Staphylococcal cell wall. The possibility that these on-board hydrolases and the curvature of the long contractile tails are advantageous to the phage for navigating through the cell wall of these various species of Staphylococcus is discussed.

Past work has seen over-representation of Staphylococcus aureus clinical isolates in genome and biology studies on staphylococci. Here, we show by a selective plating analysis of municipal wastewater that independent isolates representing seven other species of Staphylococcus were recovered (S. cohnii, S. equorum, S. lentus, S. nepalensis, S. sciuri, S. shinii, and S. xylosus), as readily identified in the samples. Genome sequence analysis revealed some species-specific antibiotic resistance profiles across the strains, and a bacteriophage was isolated that had a cross-species host range. Using this broad biological approach to analyze staphylococci has identified a phage with a broad killing range, and this phage is morphologically distinct from the three known types of tailed phages.

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