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Multiple modes of iron uptake by the filamentous, siderophore‐producing cyanobacterium, A nabaena sp. PCC 7120
Author(s) -
Rudolf Mareike,
Kranzler Chana,
Lis Hagar,
Margulis Ketty,
Stevanovic Mara,
Keren Nir,
Schleiff Enrico
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13049
Subject(s) - siderophore , biology , cyanobacteria , microbiology and biotechnology , computational biology , bacteria , genetics
Summary Iron is a member of a small group of nutrients that limits aquatic primary production. Mechanisms for utilizing iron have to be efficient and adapted according to the ecological niche. In respect to iron acquisition cyanobacteria, prokaryotic oxygen evolving photosynthetic organisms can be divided into siderophore‐ and non‐siderophore‐producing strains. The results presented in this paper suggest that the situation is far more complex. To understand the bioavailability of different iron substrates and the advantages of various uptake strategies, we examined iron uptake mechanisms in the siderophore‐producing cyanobacterium A nabaena sp. PCC 7120. Comparison of the uptake of iron complexed with exogenous (desferrioxamine B , DFB ) or to self‐secreted (schizokinen) siderophores by A nabaena sp. revealed that uptake of the endogenous produced siderophore complexed to iron is more efficient. In addition, A nabaena sp. is able to take up dissolved, ferric iron hydroxide species ( F e′) via a reductive mechanism. Thus, A nabaena sp. exhibits both, siderophore‐ and non‐siderophore‐mediated iron uptake. While assimilation of F e′ and FeDFB are not induced by iron starvation, FeSchizokinen uptake rates increase with increasing iron starvation. Consequently, we suggest that Fe′ reduction and uptake is advantageous for low‐density cultures, while at higher densities siderophore uptake is preferred.