High diversity and novel species of Pseudomonas aeruginosa bacteriophages

Abstract

The diversity of Pseudomonas aeruginosa bacteriophages was investigated using a collection of 68 phages isolated from Central Mexico. Most of the phages carried double-stranded DNA (dsDNA) genomes and were classified into 12 species. Comparison of the genomes of selected archetypal phages with extant sequences in GenBank resulted in the identification of six novel species. This finding increased the group diversity by ~30%. The great diversity of phage species could be related to the ubiquitous nature of P. aeruginosa.

Fig 1

Electron microscope images of selected phages. Each row shows three examples of the morphological family indicated in the left margin. Each percentage corresponds to the proportion of phages in the collection belonging to each family. The upper left corners are marked with the name and morphotype of the phage in each picture. Magnification, ×100,000. Bar = 50 nm.

Fig 2

Similarity dendrogram of EcoRI-generated RFLPs of 46 phages with restrictable DNAs. The RFLPs of four reference phages (F8, D3, D3112, and F10) were included in the groups within which they showed similarity. The dashed vertical line denotes the similarity threshold (61%) used to define the groups. All the branches to the right of the threshold were included in the same group. The names of the archetypal phages for each group are shown in the left margin. Columns to the right of the RFLP pictures indicate phage characteristics and sample sources. Boxed phage names indicate 100% RFLP similarity. Morphology was based on electron microscopy. Genome lengths were estimated by adding the sizes of individual restriction fragments. Sources: Gto, Guanajuato; Jal, Jalisco; Qro, Queretaro; DF, Distrito Federal; Finl, Finland; Aust, Australia; Rus, Russia.