Characterization and Genome Structure of Virulent Phage EspM4VN to Control Enterobacter sp. M4 Isolated From Plant Soft Rot

Abstract

Enterobacter sp. M4 and other bacterial strains were isolated from plant soft rot disease. Virulent phages such as EspM4VN isolated from soil are trending biological controls for plant disease. This phage has an icosahedral head (100 nm in diameter), a neck, and a contractile sheath (100 nm long and 18 nm wide). It belongs to the Ackermannviridae family and resembles Shigella phage Ag3 and Dickeya phages JA15 and XF4. We report herein that EspM4VN was stable from 10 • C to 50 • C and pH 4 to 10 but deactivated at 70 • C and pH 3 and 12. This phage formed clear plaques only on Enterobacter sp. M4 among tested bacterial strains. A one-step growth curve showed that the latent phase was 20 min, rise period was 10 min, and an average of 122 phage particles were released from each absorbed cell. We found the phage's genome size was 160,766 bp and that it annotated 219 open reading frames. The genome organization of EspM4VN has high similarity with the Salmonella phage SKML-39; Dickeya phages Coodle, PP35, JA15, and Limestone; and Shigella phage Ag3. The phage EspM4VN has five tRNA species, four tail-spike proteins, and a thymidylate synthase. Phylogenetic analysis based on structural proteins and enzymes indicated that EspM4VN was identified as a member of the genus Agtrevirus, subfamily Aglimvirinae, family Ackermannviridae.

Subtypes of tail spike proteins predicts the host range of Ackermannviridae phages

“…Our analysis revealed that all Limestonevirus phages express TSP1-26, thus the results suggest that all phages in the Limestonevirus genus can bind and degrade this LPS. This is in accordance with the known hosts of almost all Limestonevirus phages [14] , [31] , [47] , [48] , [49] , [50] , [51] , [52] , [53] . Finally, TSP2 (TSP2-18) of taipeivirus 0507KN21 recognize the KN2 capsular polysaccharide [17] .…”

Isolation and Characterization of Soil-Borne Lytic Bacteriophages Infecting Enterobacter spp. Causing Fire Blight like Disease on Apple in Egypt

“…Phages completely lost their viability at PH 3 and 13. Our results had agreement with [19] who found that a phage F20 virulent to Enterobacter aerogenes was stable over a broad range of pH from 4 to 11 and with [21] who reported that Enterobacter sp. M4 phage (EspM4VN) was stable from pH 4 to 10 but deactivated at pH 3 and 12.…”

“…Only about 30 to 50 % of phage particles survived after treatment at 55 ᴼ C. These findings indicated the high thermal tolerability of isolated phages. Comparatively, thermostable phages from the family Siphoviridae were reported to be stable at 60 ᴼC but their titers were dramatically decreased by 50% at 70 ᴼC [39], also [21] reported that Enterobacter sp. M4 phage (EspM4VN) kept stable infectivity at temperatures 10-50ᴼC but deactivated at 70 ᴼC.…”

“…EspM4VN virulent phage against Enterobacter sp. M4 caused plant soft rot disease was isolated from soil and characterized [21].…”

Phage Revolution Against Multidrug-Resistant Clinical Pathogens in Southeast Asia

“…In SEA, novel phages have been screened using WGS for their lysogenic and endotoxin production potentials (Gan et al, 2013;Lal et al, 2016a;Wirjon et al, 2016;Thanh et al, 2020;Dewanggana et al, 2021;Nuidate et al, 2021), which are important properties to avoid in choosing therapeutic phages. WGS can also aid in the more detailed classification and identification of the phages, as also applied in SEA strains with promising therapeutic potentials (Gan et al, 2013;Hoai et al, 2016;Lal et al, 2016a,b;Wirjon et al, 2016;Sellvam et al, 2018;Handoko et al, 2019;Thanh et al, 2020;Tu et al, 2020;Nuidate et al, 2021). Metagenomic sequencing of phages in the prospect samples will be helpful in the initial screening of phage genomes even before the isolation of the actual virions.…”