School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
Environ Sci Technol. 2011 Feb 15;45(4):1391-8. doi: 10.1021/es103311h. Epub 2011 Jan 25.
Visible light was observed to induce reductive dissociation of organically complexed Fe and dramatically increase the short-term uptake rate of radiolabeled Fe by Microcystis aeruginosa PCC7806 in Fraquil* medium buffered by a single metal chelator, ethylenediaminetetraacetic acid (EDTA). Only wavelengths <500 nm activated Fe uptake indicating that Fe photochemistry rather than biological factors is responsible for the facilitated uptake. The measured rate of photochemical Fe(II) production combined with a significant decrease in (55)Fe uptake rate in the presence of ferrozine (a strong ferrous iron chelator) confirmed that photogenerated unchelated Fe(II) was the major form of Fe taken up by M. aeruginosa under the conditions examined. Mathematical modeling based on unchelated Fe(II) uptake by concentration gradient dependent passive diffusion of Fe(II) through nonspecific transmembrane channels (porins) could account for the magnitude of Fe uptake and a variety of other observations such as the effect of competing ligands on Fe uptake. Steady-state uptake rates indicated that M. aeruginosa acquires Fe predominantly during the light cycle. This study confirms that Fe photochemistry has a dominant impact on Fe acquisition and growth by M. aeruginosa in EDTA-buffered culture medium.
可见光被观察到诱导有机络合铁的还原解离，并显著增加了 Microcystis aeruginosa PCC7806 在 Fraquil*培养基中放射性标记铁的短期摄取率，该培养基由单一金属络合剂乙二胺四乙酸（EDTA）缓冲。只有 <500nm 的波长激活了铁的摄取，表明是铁的光化学而不是生物因素导致了促进的摄取。测量的光化学 Fe(II)生成速率结合在存在亚铁嗪（一种强二价铁络合剂）时（55）Fe 摄取速率的显著下降，证实了在研究条件下，光生成的未络合 Fe(II)是被 M. aeruginosa 吸收的主要铁形式。基于无络合 Fe(II)通过非特异性跨膜通道（孔蛋白）的浓度梯度依赖的被动扩散摄取的数学模型可以解释铁摄取的幅度和其他各种观察结果，例如竞争配体对铁摄取的影响。稳态摄取速率表明，M. aeruginosa 主要在光照周期中获取铁。这项研究证实，铁的光化学对 M. aeruginosa 在 EDTA 缓冲培养基中获取铁和生长有主导影响。
