Summary Phosphorus ( P ) availability drives niche differentiation in the most abundant phytoplankter in the oceans, the marine cyanobacterium P rochlorococcus . We compared the molecular response of P rochlorococcus strain MED4 to P starvation in batch culture to P ‐limited growth in chemostat culture. We also identified an outer membrane porin, PMM0709 , which may allow transport of organic phosphorous compounds, rather than...

Summary Recent measurements of natural populations of the marine cyanobacterium P rochlorococcus indicate this numerically dominant phototroph assimilates phosphorus ( P ) at significant rates in P ‐limited oceanic regions. To better understand uptake capabilities of P rochlorococcus under different P stress conditions, uptake kinetic experiments were performed on P rochlorococcus MED4 grown in P ‐limited chemostats and batch...