Ferret Claire, Sterckeman Thibault, Cornu Jean-Yves, Gangloff Sophie, Schalk Isabelle J, Geoffroy Valérie A
Environ Microbiol Rep. 2014 Oct;6(5):459-67. doi: 10.1111/1758-2229.12146.
Siderophores are organic chelators produced by microorganisms to fulfil their iron requirements. Siderophore-promoted dissolution of iron-bearing minerals has been clearly documented for some siderophores, but few studies have addressed metabolizing siderophore-producing bacteria. We investigated iron acquisition from clays by fluorescent Pseudomonads, bacteria that are ubiquitous in the environment. We focused on the interactions between smectite and Pseudomonas aeruginosa, a bacterium producing two structurally different siderophores: pyoverdine and pyochelin. The presence of smectite in iron-limited growth media promoted planktonic growth of P. aeruginosa and biofilm surrounding the smectite aggregates. Chemical analysis of the culture media indicated increases in the dissolved silicon, iron and aluminium concentrations following smectite supplementation. The use of P. aeruginosa mutants unable to produce either one or both of the two siderophores indicated that pyoverdine, the siderophore with the higher affinity for iron, was involved in iron and aluminium solubilization by the wild-type strain. However, in the absence of pyoverdine, pyochelin was also able to solubilize iron but with a twofold lower efficiency. In conclusion, pyoverdine and pyochelin, two structurally different siderophores, can solubilize structural iron from smectite and thereby make it available for bacterial growth.
铁载体是微生物产生的有机螯合剂，用于满足其铁需求。一些铁载体促进含铁矿物溶解的现象已有明确记载，但针对代谢产铁载体细菌的研究却很少。我们研究了荧光假单胞菌从黏土中获取铁的情况，这类细菌在环境中普遍存在。我们重点关注了蒙脱石与铜绿假单胞菌之间的相互作用，铜绿假单胞菌是一种能产生两种结构不同铁载体（绿脓菌素和焦铁素）的细菌。在缺铁生长培养基中添加蒙脱石促进了铜绿假单胞菌的浮游生长以及蒙脱石聚集体周围生物膜的形成。对培养基的化学分析表明，添加蒙脱石后溶解的硅、铁和铝浓度有所增加。使用无法产生这两种铁载体中的一种或两种的铜绿假单胞菌突变体表明，对铁亲和力较高的铁载体绿脓菌素参与了野生型菌株对铁和铝的溶解。然而，在没有绿脓菌素的情况下，焦铁素也能够溶解铁，但效率要低两倍。总之, 绿脓菌素和焦铁素这两种结构不同的铁载体，能够溶解蒙脱石中的结构铁，从而使其可用于细菌生长。
