Characterization and genomic analyses of two newly isolated Morganella phages define distant members among Tevenvirinae and Autographivirinae subfamilies

Abstract

Morganella morganii is a common but frequent neglected environmental opportunistic pathogen which can cause deadly nosocomial infections. The increased number of multidrug-resistant M. morganii isolates motivates the search for alternative and effective antibacterials. We have isolated two novel obligatorily lytic M. morganii bacteriophages (vB_MmoM_MP1, vB_MmoP_MP2) and characterized them with respect to specificity, morphology, genome organization and phylogenetic relationships. MP1’s dsDNA genome consists of 163,095 bp and encodes 271 proteins, exhibiting low DNA (<40%) and protein (<70%) homology to other members of the Tevenvirinae. Its unique property is a >10 kb chromosomal inversion that encompass the baseplate assembly and head outer capsid synthesis genes when compared to other T-even bacteriophages. MP2 has a dsDNA molecule with 39,394 bp and encodes 55 proteins, presenting significant genomic (70%) and proteomic identity (86%) but only to Morganella bacteriophage MmP1. MP1 and MP2 are then novel members of Tevenvirinae and Autographivirinae, respectively, but differ significantly from other tailed bacteriophages of these subfamilies to warrant proposing new genera. Both bacteriophages together could propagate in 23 of 27 M. morganii clinical isolates of different origin and antibiotic resistance profiles, making them suitable for further studies on a development of bacteriophage cocktail for potential therapeutic applications.

Characterization of the Three New Kayviruses and Their Lytic Activity Against Multidrug-Resistant Staphylococcus aureus

“…Furthermore, it was found that isolated phages have a wide host range among MDRSA isolates collected from different clinical sites, both from inpatients and outpatients which is in accordance with other staphylococcal K-like phages [9,16,18]. Though it was proven that selected spot test method, when spotting high titer lysates (10 9 PFU/mL), can generate false positive results correlated with abortive infection, lysis from without, and enzyme activity [48] it is still used to screen the bactericidal ability of the isolated phages [25,49,50]. Moreover, applying phages at lower concentrations prevents from the overestimation of phage sensitivity [51].…”

A Tailspike with Exopolysaccharide Depolymerase Activity from a New Providencia stuartii Phage Makes Multidrug-Resistant Bacteria Susceptible to Serum-Mediated Killing

“…Transmission electron microscopy. Transmission electron micrographs (TEM) of phage Stuart were captured using a JEM-1400 microscope (JEOL, Tokyo, Japan) exactly as previously described (44). Lysates were centrifuged (1 h, 25,000 ϫ g, 4°C) to pellet phages and then washed twice with tap water.…”

Targeting mechanisms of tailed bacteriophages

“…RBP phage-encoded enzymes. Tailed phages of both Gram-negative and Gram-positive bacteria commonly harbour peptidoglycan-degrading enzymes, including endopeptidases 81 , N-acetylmuramyl-l-alanine amidases 82 , N-acetylglycosaminidase 83,84 , lysozymes 85 and lytic transglycosylases 86 . These enzymes locally degrade or rearrange peptidoglycan 87 , and although they are not always required for infection, they provide advantages under particular conditions.…”