SAR11 bacteria thrive — despite viruses

Bacteria of the SAR11 clade — named originally following their discovery in the Sargasso Sea — are by far the most abundant microbes in the world's oceans, and as such are an important factor in carbon cycling. This study describes the isolation and subsequent culture of several viruses that infect SAR11 from water samples taken on the Oregon coast and off Bermuda. Metagenomic analysis reveals that these 'pelagiphages' are abundant in the Pacific Ocean. These findings argue against a recent hypothesis developed to explain the success of SAR11 — that they might be immune to viral predation. Rather, the authors suggest, SAR1's dominance may reflect successfully evolved adaptation to resource competition.