Issue 6, 2014

Distributions of iron, phosphorus and sulfur along trichomes of the cyanobacteria Trichodesmium

Abstract

The nonheterocystous cyanobacterium Trichodesmium fixes C and N concurrently during the light period in tropical and subtropical oceans. Synchrotron mapping of Fe, P and S in trichomes of Trichodesmium erythraeum Erhenberg IMS 101 (CCMP 1985) collected during exponential and senescent growth revealed that 16% of trichomes contained sections of up to 25 cells with ca. 2-fold elevated Fe and S but ca. 2-fold lowered P in comparison to neighboring trichome sections. The correlation between Fe and S in these trichomes was moderate to strongly positive (R > 0.35), while the correlation between Fe and P was moderate to strongly negative (R < 0.35). Higher Fe in theses trichome sections might indicate the presence of nitrogenase. Increase in S in conjunction with Fe is likely driven by other S-containing compounds in addition to Fe–S proteins. Furthermore, the concurrent increase in S and decrease in P in these Fe-rich trichome sections might indicate a switch from P- to S-containing compounds. Diurnal changes and growth phase-related differences in the correlation between Fe and P both point to Trichodesmium's ability to re-allocate elements depending on their physiological need. Concurrent P depletion and Fe and S enrichment in trichome sections is a strong indication that Trichodesmium is able to develop special trichome regions consisting of multiple cells with a unique chemical composition. Whether these cells are uniquely dedicated to N2-fixation (i.e., diazocytes) is an open question.

Graphical abstract: Distributions of iron, phosphorus and sulfur along trichomes of the cyanobacteria Trichodesmium

Supplementary files

Article information

Article type
Paper
Submitted
14 Feb 2014
Accepted
24 Apr 2014
First published
24 Apr 2014

Metallomics, 2014,6, 1141-1149

Author version available

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