Single-cell-resolved frequency and modes of phage interactions with prokaryoplankton in the tropical surface ocean

Marine planktonic viruses have a significant impact on microbial communities and global biogeochemical cycles. Researchers have now conducted an in-depth analysis of the interactions between marine prokaryoplankton and viruses in the tropical surface ocean using GORG-Tropics, a global collection of 12,715 single amplified genomes (SAGs) derived from randomly sampled marine prokaryoplankton cells.

The study found that 4.2% of the SAGs contained phage genomic material, with the highest frequency in productive ocean regions. Prokaryoplankton lineages with high metabolic rates, such as Prochlorococcus and Rhodobacterales, had a larger fraction of cells associated with viruses, particularly compared to the less active but highly abundant Pelagibacterales.

Cell-virus associations indicative of lysogeny were more common in Alphaproteobacteria. The genomic diversity of recovered phages spanned order-level taxonomies, suggesting a high degree of diversity and connectivity within wild phage populations. Interestingly, a significant portion of the observed cell-virus associations did not align with the computationally predicted host identity, indicating non-infective interactions.

This research provides substantial evidence of viral infection rates in the prokaryoplankton community across the global surface tropical ocean, also uncovering non-infective phage-cell associations that may contribute to lateral transfer of viral genes and nutrition for marine prokaryoplankton.