Data from: Evolving interactions between diazotrophic cyanobacterium and phage mediate nitrogen release and host competitive ability

Interactions between nitrogen-fixing (i.e. diazotrophic) cyanobacteria and
their viruses, cyanophages, can have large-scale ecosystem effects. These
effects are mediated by temporal alterations in nutrient availability in
aquatic systems owing to the release of nitrogen and carbon sources from
cells lysed by phages, as well as by ecologically important changes in the
diversity and fitness of cyanobacterial populations that evolve in the
presence of phages. However, ecological and evolutionary feedbacks between
phages and nitrogen-fixing cyanobacteria are still relative poorly
understood. Here, we used an experimental evolution approach to test the
effect of interactions between a common filamentous, nitrogen-fixing
cyanobacterium (Nodularia sp.) and its phage on cellular nitrogen release
and host properties. Ecological, community-level effects of phage-mediated
nitrogen release were tested with a phytoplankton bioassay. We found that
cyanobacterial nitrogen release increased significantly as a result of
viral lysis, which was associated with enhanced growth of phytoplankton
species in cell-free filtrates compared with phage-resistant host controls
in which lysis and subsequent nutrient release did not occur after phage
exposure. We also observed an ecologically important change among
phage-evolved cyanobacteria with phage-resistant phenotypes, a
short-filamentous morphotype with reduced buoyancy compared with the
ancestral long-filamentous morphotype. Reduced buoyancy might decrease the
ability of these morphotypes to compete for light compared with longer,
more buoyant filaments. Together, these findings demonstrate the potential
of cyanobacteria–phage interactions to affect ecosystem biogeochemical
cycles and planktonic community dynamics.