Wide Distribution of Phage That Infect Freshwater SAR11 Bacteria.

(LD12 subclade) is among the most abundant bacterioplankton in freshwater ecosystems. These bacteria belong to the order (SAR11) and are related to (marine SAR11), which dominates many marine habitats. Although a few phage (Pelagiphage) have been described, no phage that infect have been reported. In this study, we describe two groups of phage that infect A complete genome containing a prophage was reconstructed from metagenomic data. A circularized and complete genome related to the prophage, referred to as uv-Fonsiphage-EPL (lysogenic strategy), shows high similarity to marine Pelagiphage HTVC025P. Additionally, we reconstructed three complete genomes and one draft genome of phage related to marine Pelagiphage HTVC010P and predicted a lytic strategy. The similarity in codon usage and cooccurrence patterns of HTVC010P-related phage and suggested that these phage infect Similar phage were detected in Lake Mendota, Wisconsin, where is also present. A search of related phage revealed the worldwide distribution of some genotypes in freshwater ecosystems, suggesting their substantial role in shaping indigenous microbial assemblages and influence on biogeochemical cycling. However, the uv-Fonsiphage-EPL and one group of HTVC010P-related phage have a more limited distribution in freshwater ecosystems. Overall, the findings provide insights into the genomic features of phage that infect and expand understanding of the ecology and evolution of these important bacteria. represents a significant microbial group of freshwater ecosystems. Although the genomic and metabolic features of these bacteria have been well studied, no phage infecting them has been reported. In this study, we reconstructed complete genomes of and infecting phage and revealed their close relatedness to the phage infecting marine SAR11 members. Also, we illustrated that phage that infect are widely distributed in freshwater habitats. In summary, the results contribute new insights into the ecology and evolution of and phage.