Raphidiopsis raciborskii is an invasive bloom‐forming cyanobacteria with the flexibility to utilize atmospheric and fixed nitrogen. Since nitrogen‐fixation has a high requirement for iron as an ezyme cofactor, we hypothesize that iron availability would determine the success of the species under nitrogen‐fixing conditions. This study compares the proteomic response of cylindrospermopsin‐producing and non‐toxic strains of R. racibroskii to reduced iron concentrations, under nitrogen‐fixing conditions, to examine any strain‐specific adaptations that might increase fitness under these conditions. We also compared their proteomic responses at exponential and stationary growth phases to capture the changes throughout the growth cycle. Overall, the toxic strain was more competitive under Fe‐starved conditions during exponential phase, with upregulated growth and transport‐related proteins. The non‐toxic strain showed reduced protein expression across multiple primary metabolism pathways. We propose that the increased expression of porin proteins during the exponential growth phase enables toxic strains to persist under Fe‐starved conditions with this ability providing a potential explanation for the increased fitness of cylindrospermoipsin‐producing strains during unfavourable environmental conditions.

中文翻译：

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产铁重氮菌Raphidiopsis raciborskii（蓝细菌）对铁的响应的比较蛋白质组学

Raphidiopsis raciborskii是一种侵入性开花形成性蓝细菌，可以灵活利用大气和固定氮。由于固氮对铁作为酶的辅助因子有很高的要求，因此我们假设铁的可用性将决定固氮条件下物种的成功。这项研究比较了生产环精子藻和无毒罗非鱼的蛋白质组学反应。在固氮条件下降低铁浓度，以检查在这些条件下可能增加适应性的任何菌株特异性适应性。我们还比较了它们在指数生长期和静止生长期的蛋白质组学反应，以捕获整个生长期的变化。总体而言，在铁缺乏的条件下，该毒株在指数期更具竞争性，其生长和运输相关蛋白上调。该无毒菌株在多个主要代谢途径中均显示出蛋白质表达降低。