A Comparative Study of Iron Uptake Rates and Mechanisms amongst Marine and Fresh Water Cyanobacteria: Prevalence of Reductive Iron Uptake

Life

Hagar Lis³  Chana Kranzler³  Nir Keren¹  Yeala Shaked³  John C. Meeks² 

[1]Department of Plant and Environmental Sciences, Institute of Life Science, The Hebrew University of Jerusalem, Jerusalem 91904, Israel

[2] E-Mail:Interuniversity Institute for Marine Sciences in Eilat, Israel

[3]

[4]Interuniversity Institute for Marine Sciences in Eilat, Israel

[5] E-Mails:

关键词: cyanobacteria;    iron;    siderophore;    reduction;    phytoplankton;    iron uptake;   

DOI  :  10.3390/life5010841

来源: mdpi

【 摘 要 】

In this contribution, we address the question of iron bioavailability to cyanobacteria by measuring Fe uptake rates and probing for a reductive uptake pathway in diverse cyanobacterial species. We examined three Fe-substrates: dissolved inorganic iron (Fe') and the Fe-siderophores Ferrioxamine B (FOB) and FeAerobactin (FeAB). In order to compare across substrates and strains, we extracted uptake rate constants (k_in = uptake rate/[Fe-substrate]). Fe' was the most bioavailable Fe form to cyanobacteria, with k_in values higher than those of other substrates. When accounting for surface area (SA), all strains acquired Fe' at similar rates, as their k_in/SA were similar. We also observed homogeneity in the uptake of FOB among strains, but with 10,000 times lower k_in/SA values than Fe'. Uniformity in k_in/SA suggests similarity in the mechanism of uptake and indeed, all strains were found to employ a reductive step in the uptake of Fe' and FOB. In contrast, different uptake pathways were found for FeAB along with variations in k_in/SA. Our data supports the existence of a common reductive Fe uptake pathway amongst cyanobacteria, functioning alone or in addition to siderophore-mediated uptake. Cyanobacteria combining both uptake strategies benefit from increased flexibility in accessing different Fe-substrates.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.