Abundance and ecological footprint of Pseudoalteromonas phage vB_PhoS_XC in the Ulva prolifera green tide

Abstract

Pseudoalteromonas is a ubiquitous and abundant genus of marine bacteria commonly associated with algae. In this study, a novel siphoviral-morphological bacteriophage, vB_PhoS_XC, was isolated from the coastal seawaters of Qingdao (China) during a bloom of the Ulva prolifera (U. prolifera) green tide. The morphology of this phage (icosahedron head 51 ± 1 nm in diameter; a tail length of 86 ± 1 nm) was characterized through transmission electron microscope. The biological properties of this virus showed a short latent period (45 minutes), a large burst size (241 virions per cell) and a relatively wide range of temperatures/pH level tolerance (-20°C to 45°C and pH 4 to pH 10, respectively). The vB_PhoS_XC has a 46,490-bp double-stranded DNA genome with a G+C content of 40.0%, and encodes 72 open reading frames (ORFs). Thirty-five of these ORFs were assigned into known functions based on BLAST-based algorithm against NR database of GenBank. In addition, eco-genomic analysis provides the evidence of vB_PhoS_XC accompanied by bloom of U. prolifera, and confirmed the high expression of two phosphatase-metabolism-related auxiliary metabolic genes (AMGs). This study provides new insights into the functional and ecological roles of the Pseudoalteromonas phage vB_PhoS_XC, shedding light on the virological study approach combined with traditional isolation and meta-omics data.

A novel flavobacterial phage abundant during green tide, representing a new viral family, Zblingviridae

“…Several phages with higher abundance in the ocean were selected as references, including representative pelagibacter phages (HTVC010P, HTVC019P, HTVC011P, and HTVC008M), cyanophages (P-SSB7, P-SSM7, and S-RIM4) ( 48 ), Synechococcus phages (S-ShM2, S-SSM5, P60, S-B28, and S-B68), Prochlorococcus phages (P-HM1, P-HM2, P-RSM4, P-SSM2, and P-SSM4), and some closely related flavophages (vB_FspS_snusmum6-1, vB_FspS_snusmum6-1, vB_FspS_mumin9-1, vB_FspS_hattifnatt9-1, vB_FspS_tooticki6-1, and vB_S_filifjonk9-1), as well as four non-redundant homology uncultured viral genomes (UViGs) taxonomically associated with vB_TgeS_JQ. We also calculated the relative abundances of vB_TgeS_JQ and its closely related flavophages based on several virus metagenomic data during outbreak and the extinction process of U. prolifera in coastal Qingdao in 2020 ( 49 ).…”