Novel pelagiphage isolate Polarivirus skadi is a polar specialist that dominates SAR11-associated bacteriophage communities at high latitudes

Abstract

The SAR11 clade are the most abundant members of surface marine bacterioplankton and a critical component of global biogeochemical cycles. Similarly, pelagiphages that infect SAR11 are ubiquitous and highly abundant in the oceans. Pelagiphages are predicted to shape SAR11 community structures and increase carbon turnover throughout the oceans. Yet, ecological drivers of host and niche specificity of pelagiphage populations are poorly understood. Here we report the global distribution of a novel pelagiphage called “Polarivirus skadi”, which is the sole representative of a novel genus. P. skadi was isolated from the Western English Channel using a cold-water ecotype of SAR11 as bait. P. skadi is closely related to the globally dominant pelagiphage HTVC010P. Along with other HTVC010P-type viruses, P. skadi belongs to a distinct viral family within the order Caudovirales, for which we propose the name Ubiqueviridae. Metagenomic read recruitment identified P. skadi as one of the most abundant pelagiphages on Earth. P. skadi is a polar specialist, replacing HTVC010P at high latitudes. Experimental evaluation of P. skadi host range against cold- and warm-water SAR11 ecotypes supported cold-water specialism. Relative abundance of P. skadi in marine metagenomes correlated negatively with temperature, and positively with nutrients, available oxygen, and chlorophyll concentrations. In contrast, relative abundance of HTVC010P correlated negatively with oxygen and positively with salinity, with no significant correlation to temperature. The majority of other pelagiphages were scarce in most marine provinces, with a few representatives constrained to discrete ecological niches. Our results suggest that pelagiphage populations persist within a global viral seed bank, with environmental parameters and host availability selecting for a few ecotypes that dominate ocean viromes.

Identification and genomic analysis of temperate Halomonas bacteriophage vB_HmeY_H4907 from the surface sediment of the Mariana Trench at a depth of 8,900 m

“…4A ). The phage VB_HmeY_H4907 most likely represented a novel family under Caudoviricetes viruses, according to ICTV, which classifies phages with >70% nucleotide sequence identity as belonging to the same genus ( 48 , 49 ). Therefore, the phage vB_HmeY_H4907 constitutes a novel family of Caudoviricetes, which we will refer to as the Suviridae .…”

Ecological Interaction between Bacteriophages and Bacteria in Sub-Arctic Kongsfjorden Bay, Svalbard, Norway

“…The presence of Pelagibacter phage HTVC008M and Puniceispirillum phage HMO-2011, including the Pelagibacter phage group, suggests that the SAR11 bacterial group is abundant in the Arctic Ocean [ 56 ]. The co-occurrence of various phages with various bacteria indicates that phages may be capable of infecting multiple host bacterial ecotypes in warm- and cold-water environments [ 57 ]. In this study, Puniceispirillum phage HMO-2011, Pelagibacter phage HTBC010P, Puniceispirillum phage HMO-2011, Vibrio phage CHOED, and Roseobacter virus SIO1 were strongly associated with Sulfitobacter and Loktanella.…”

The structure and assembly mechanisms of T4-like cyanophages community in the South China Sea

“…Viruses are the most abundant biological entities on the earth and play critical roles across diverse ecosystems by altering microbial population structure, mortality, and evolution ( 1 – 4 ). The global comparison of viral metagenomic data observed biogeographic differences of marine viruses ( 5 , 6 ), such as the latitudinal biogeography of SAR11 phage ( 7 – 9 ). Cyanobacteria account for a large portion of global carbon fixation.…”