Two novel phages infecting Erythrobacter isolated from the epipelagic ocean

TL;DR

This paper describes two new phages that infect Erythrobacter bacteria found in coastal seawater, expanding our knowledge of marine phage diversity and their ecological roles.

Contribution

The study isolates and characterizes two novel phages, R34L1 and R34L2, and identifies them as members of a new viral genus, Eausmariqdvirus.

Findings

R34L1 and R34L2 have distinct but similar genomes and host ranges, with high genome similarity (99.73%).

The phages belong to a new viral genus, Eausmariqdvirus, and are prevalent in temperate and tropical epipelagic ocean regions.

Abstract

Erythrobacter, an aerobic anoxygenic photoheterotrophic bacterial genus, plays a vital role in carbon and energy cycling in marine environments. However, their phage predators remain poorly understood, with only two strains previously reported. This study isolated and characterized a novel Erythrobacter phage, vB_EauS-R34L1 (R34L1), and its sub-strain vB_EauS-R34L2 (R34L2), from coastal seawater. Both phages exhibit long-tailed, icosahedral morphologies and relatively narrow but slightly different host ranges. One-step growth curve analysis revealed a 160-min latent period and burst sizes of 81 and 91 PFU/cell for R34L1 and R34L2, respectively. Genomic analysis showed that the phages possess dsDNA genomes of 56,415 bp (R34L1) and 54,924 bp (R34L2), with G + C contents of 61.60 and 61.19%, respectively. Both phages harbor a suite of unique genes, including GapR and GH19, which are crucial for host interaction and ecological functionality. Blastn analysis indicated a 99.73% genome similarity between them. Taxonomic and phylogenetic analyses positioned them in a novel viral genus cluster, Eausmariqdvirus, under the family Casjensviridae, indicating a distant evolutionary relationship with known phages. Metagenomic queries suggested that R34L1- and R34L2-like phages are exclusively abundant in temperate and tropical epipelagic zones. This study expands our understanding of Erythrobacter phages and provides insights into their ecological roles in marine ecosystems.

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