Co-acquisition of mineral-bound iron and phosphorus by natural Trichodesmium colonies

Yeala Shaked*, Dirk de Beer, Siyuan Wang, Futing Zhang, Anna Neva Visser, Meri Eichner, Subhajit Basu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Low iron (Fe) and phosphorus (P) ocean regions are often home to the globally important N2-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. We present a new sensitive assay to determine P uptake from particles, utilizing 33P-labeled ferrihydrite. To validate the method, we examined single natural Trichodesmium thiebautii colonies in a high-resolution radiotracer ß-imager, identifying strong colony-mineral interactions, efficient removal of external 33P-labeled ferrihydrite, and elevated 33P uptake in the colony core. Next, we determined bulk P uptake rates, comparing natural Red Sea colonies and P-limited Trichodesmium erythraeum cultures. Uptake rates by natural and cultured Trichodesmium were similar to P release rates from the mineral, suggesting tight coupling between dissolution and uptake. Finally, synthesizing P-ferrihydrite labeled with either 33P or 55Fe, we probed for Fe/P co-extraction by common microbial mineral solubilization pathways. Dissolution rates of ferrihydrite were accelerated by exogenous superoxide and strong Fe-chelator and subsequently enhanced 33P release and uptake by Trichodesmium. Our method and findings can facilitate further Fe/P co-acquisition studies and highlight the importance of biological mechanisms and microenvironments in controlling bioavailability and nutrient fluxes from particles.

Original languageAmerican English
Pages (from-to)1064-1077
Number of pages14
JournalLimnology and Oceanography
Volume68
Issue number5
DOIs
StatePublished - May 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.

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