Characterization and genomic analysis of the first Oceanospirillum phage, vB_OliS_GJ44, representing a novel siphoviral cluster

Wenjing Zhang,Chengxiang Gu,Hualong Wang,Yong Jiang,Andrew Mcminn,Hongbing Shao,Yuzhong Zhang,Hui He,Yundan Liu,Kaiyang Zheng,Cui Guo,Wen Jye Mok,Xinran Zhang,Min Wang,Ziyue Wang,Yeong Yik Sung,Yantao Liang

doi:10.1186/s12864-021-07978-4

Abstract

BackgroundMarine bacteriophages play key roles in the community structure of microorganisms, biogeochemical cycles, and the mediation of genetic diversity through horizontal gene transfer. Recently, traditional isolation methods, complemented by high-throughput sequencing metagenomics technology, have greatly increased our understanding of the diversity of bacteriophages. Oceanospirillum, within the order Oceanospirillales, are important symbiotic marine bacteria associated with hydrocarbon degradation and algal blooms, especially in polar regions. However, until now there has been no isolate of an Oceanospirillum bacteriophage, and so details of their metagenome has remained unknown.ResultsHere, we reported the first Oceanospirillum phage, vB_OliS_GJ44, which was assembled into a 33,786 bp linear dsDNA genome, which includes abundant tail-related and recombinant proteins. The recombinant module was highly adapted to the host, according to the tetranucleotides correlations. Genomic and morphological analyses identified vB_OliS_GJ44 as a siphovirus, however, due to the distant evolutionary relationship with any other known siphovirus, it is proposed that this virus could be classified as the type phage of a new Oceanospirivirus genus within the Siphoviridae family. vB_OliS_GJ44 showed synteny with six uncultured phages, which supports its representation in uncultured environmental viral contigs from metagenomics. Homologs of several vB_OliS_GJ44 genes have mostly been found in marine metagenomes, suggesting the prevalence of this phage genus in the oceans.ConclusionsThese results describe the first Oceanospirillum phage, vB_OliS_GJ44, that represents a novel viral cluster and exhibits interesting genetic features related to phage–host interactions and evolution. Thus, we propose a new viral genus Oceanospirivirus within the Siphoviridae family to reconcile this cluster, with vB_OliS_GJ44 as a representative member.

Highlights

Marine bacteriophages play key roles in the community structure of microorganisms, biogeochemical cycles, and the mediation of genetic diversity through horizontal gene transfer
The graph of transmission electron microscopy (TEM) showed an interesting and special structure in the middle of the tail, which is similar to a tail filament
B Heat map based on OrthoANI values calculated using OAT software we propose that vB_OliS_GJ44 represents a novel viral genus, named Oceanospirivirus, in the Siphoviridae

Summary

Introduction

Marine bacteriophages play key roles in the community structure of microorganisms, biogeochemical cycles, and the mediation of genetic diversity through horizontal gene transfer. From the ocean surface to the hadal zones and from the Arctic to the Antarctic, viruses are the most abundant and diverse life forms in the ocean [1, 2] They control the microbial community through infection and lysis of their hosts, which promote biogeochemical cycling through the “viral shunt” and “viral shuttle” [3]. Oceanospirillum is the type genus of the family Oceanospirillaceae, in the order Oceanospirillales of the class Gammaproteobacteria Members of this family have often been found in oil-contaminated habitats [1, 8,9,10], and are well known for their ability to degrade petroleum hydrocarbons [11]. Phages infecting other genera of Oceanospirillum have yet not been isolated

Methods

Results

Conclusion