Global niche partitioning of purine and pyrimidine cross-feeding among ocean microbes.

Cross-feeding involves microbes consuming exudates of other surrounding microbes, mediating elemental cycling. Characterizing the diversity of cross-feeding pathways in ocean microbes illuminates evolutionary forces driving self-organization of ocean ecosystems. Here, we uncover a purine and pyrimidine cross-feeding network in globally abundant groups.

Production and cross-feeding of nitrite within populations.

is an abundant photosynthetic bacterium in the open ocean, where nitrogen (N) often limits phytoplankton growth. In the low-light-adapted LLI clade of , nearly all cells can assimilate nitrite (NO), with a subset capable of assimilating nitrate (NO). LLI cells are maximally abundant near the primary NO maximum layer, an oceanographic feature that may, in part, be due to incomplete assimilatory NO reduction and subsequent NO release by phytoplankton.

Coping with darkness: The adaptive response of marine picocyanobacteria to repeated light energy deprivation.

The picocyanobacteria and are found throughout the ocean's euphotic zone, where the daily light:dark cycle drives their physiology. Periodic deep mixing events can, however, move cells below this region, depriving them of light for extended periods of time. Here, we demonstrate that members of these genera can adapt to tolerate repeated periods of light energy deprivation.