Shewanella phage encoding a putative anti-CRISPR-like gene represents a novel potential viral family.

Abstract

Shewanella is a prevalent bacterial genus in deep-sea environments including marine sediments, exhibiting diverse metabolic capabilities that indicate its significant contributions to the marine biogeochemical cycles. However, only a few Shewanella phages were isolated and deposited in the NCBI database. In this study, we report the isolation and characterization of a novel Shewanella phage, vB_SbaS_Y11, that infects Shewanella KR11 and was isolated from the sewage in Qingdao, China. Transmission electron microscopy revealed that vB_SbaS_Y11 has an icosahedral head and a long tail. The genome of vB_SbaS_Y11 is a linear, double-stranded DNA with a length of 62,799 bp and a G+C content of 46.9%, encoding 71 putative open reading frames. No tRNA genes or integrase-related feature genes were identified. An uncharacterized anti-CRISPR AcrVA2 gene was detected in its genome. Phylogenetic analysis based on the amino acid sequences of whole genomes and comparative genomic analyses indicate that vB_SbaS_Y11 has a novel genomic architecture and shares low similarity to Pseudomonas virus H66 and Pseudomonas phage F116. vB_SbaS_Y11 represents a potential new family-level virus cluster with eight metagenomic assembled viral genomes named Ranviridae.IMPORTANCEThe Gram-negative Shewanella bacterial genus currently includes about 80 species of mostly aquatic Gammaproteobacteria, which were isolated around the globe in a multitude of environments, such as freshwater, seawater, coastal sediments, and the deepest trenches. Here, we present a Shewanella phage vB_SbaS_Y11 that contains an uncharacterized anti-CRISPR AcrVA2 gene and belongs to a potential virus family, Ranviridae. This study will enhance the knowledge about the genome, diversity, taxonomic classification, and global distribution of Shewanella phage populations.