N₂ fixation in free-floating filaments of Trichodesmium is higher than in transiently suboxic colony microenvironments.

ABSTRACT: To understand the role of micrometer-scale oxygen (O₂ ) gradients in facilitating dinitrogen (N₂ ) fixation, we characterized O₂ dynamics in the microenvironment around free-floating trichomes and colonies of Trichodesmium erythraeum IMS101. Diurnal and spatial variability in O₂ concentrations in the bulk medium, within colonies, along trichomes and within single cells were determined using O₂ optodes, microsensors and model calculations. Carbon (C) and N₂ fixation as well as O₂ evolution and uptake under different O₂ concentrations were analyzed by stable isotope incubations and membrane inlet mass spectrometry. We observed a pronounced diel rhythm in O₂ fluxes, with net O₂ evolut

SUBMITTER: Eichner M 

PROVIDER: S-EPMC6590460 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature