To protect the O 2 ‐sensitive nitrogenase enzyme, diazotrophic cyanobacteria separate N 2 fixation from photosynthesis in space or time. However, in the filamentous Trichodesmium , technical limitations and conflicting results have so far prevented a consensus on the separation mechanism. Here, we specifically adapted single‐cell methods for simultaneously capturing both photosynthesis and N 2 fixation at the levels of gene ex...

Aerosol dust deposited on the nutrient‐deprived surface ocean can boost phytoplankton growth and oceanic carbon uptake. Low mineral solubility restricts the biological utilization of dust‐nutrients, thereby benefiting phytoplankton that actively dissolve dust. The ubiquitous colony‐forming, N 2 ‐fixing cyanobacteria Trichodesmium specialize in dust‐nutrient utilization, with several dust‐dissolution pathways identified in natu...

Low iron (Fe) and phosphorus (P) ocean regions are often home to the globally important N 2 ‐fixing cyanobacterium Trichodesmium spp., which are physiologically adapted to Fe/P co‐limitation. Given Trichodesmium 's eminent ability to capture particles and the common associations between Fe and P in sediments and aerosols, we hypothesized that mineral bio‐dissolution by Trichodesmium spp. may enable them to co‐acquire Fe and P....

Photosynthesis and respiration cause distinct chemical microenvironments within cyanobacterial aggregates. Here, we used microsensors and a diffusion–reaction model to characterize gradients in carbonate chemistry and investigate how these are affected by ocean acidification in Baltic vs. Pacific aggregates ( Nodularia and Dolichospermum vs. Trichodesmium ). Microsensor measurements of O 2 and pH were performed under in situ a...

Colonies of the N 2 ‐fixing cyanobacterium Trichodesmium can harbor distinct chemical microenvironments that may assist the colonies in acquiring mineral iron from dust. Here, we characterized O 2 and pH gradients in and around Trichodesmium colonies by microsensor measurements on > 170 colonies collected in the Gulf of Eilat over ∼ 2 months. O 2 concentrations and pH values in the center of single colonies decreased in the da...