A Novel Broad Host Range Phage Infecting Alteromonas.

Xuejin Feng,Nianzhi Jiao,Shuzhen Wei,Anan Wang,Rui Zhang,Yi-Lung Chen,Xiaowei Chen,Wei Yan,Tao Jin,Ruijie Ma,Ta-Hui Lin

doi:10.3390/v13060987

Abstract

Bacteriophages substantially contribute to bacterial mortality in the ocean and play critical roles in global biogeochemical processes. Alteromonas is a ubiquitous bacterial genus in global tropical and temperate waters, which can cross-protect marine cyanobacteria and thus has important ecological benefits. However, little is known about the biological and ecological features of Alteromonas phages (alterophages). Here, we describe a novel alterophage vB_AmeP-R8W (R8W), which belongs to the Autographiviridae family and infects the deep-clade Alteromonas mediterranea. R8W has an equidistant and icosahedral head (65 ± 1 nm in diameter) and a short tail (12 ± 2 nm in length). The genome size of R8W is 48,825 bp, with a G + C content of 40.55%. R8W possesses three putative auxiliary metabolic genes encoding proteins involved in nucleotide metabolism and DNA binding: thymidylate synthase, nucleoside triphosphate pyrophosphohydrolase, and PhoB. R8W has a rapid lytic cycle with a burst size of 88 plaque-forming units/cell. Notably, R8W has a wide host range, such that it can infect 35 Alteromonas strains; it exhibits a strong specificity for strains isolated from deep waters. R8W has two specific receptor binding proteins and a compatible holin–endolysin system, which contribute to its wide host range. The isolation of R8W will contribute to the understanding of alterophage evolution, as well as the phage–host interactions and ecological importance of alterophages.

Highlights

Viruses are widely distributed in the oceans, with an average abundance of approximately 107 viruses mL−1 at the ocean surface [1]
A novel alterophage R8W was isolated from Xiamen Bay, China, using the deep-clade A. mediterranea DE as a host
We identified three putative auxiliary metabolic genes (AMGs) in the R8W genome: g19, g24, and g48. g19 encodes ThyX, a thymidylate synthase with two forms, ThyX and ThyA, which are primarily found in phages and bacteria, respectively

Summary

Introduction

Viruses are widely distributed in the oceans, with an average abundance of approximately 107 viruses mL−1 at the ocean surface [1]. Most marine viruses are bacteriophages that infect bacteria and cause an estimated bacterial mortality rate of 10–50% daily in the ocean [1]. Bacteriophages are exceptionally diverse, both morphologically and genetically; they can facilitate horizontal gene transfer and are important for bacterial diversity and evolution [2]. Bacteriophages play crucial roles in marine ecosystems and global biogeochemical cycles [7,8]. The marine bacteria Alteromonas, a genus within the Gammaproteobacteria belonging to a Gram-negative organism, is widely distributed in global tropical and temperate waters [9]. Alteromonas spp. are not always abundant in the

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Conclusion