Wei Xueming, Vajrala Neeraja, Hauser Loren, Sayavedra-Soto Luis A, Arp Daniel J
Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331-2902, USA.
Arch Microbiol. 2006 Aug;186(2):107-18. doi: 10.1007/s00203-006-0126-4. Epub 2006 Jun 21.
Nitrosomonas europaea, as an ammonia-oxidizing bacterium, has a high Fe requirement and has 90 genes dedicated to Fe acquisition. Under Fe-limiting conditions (0.2 microM Fe), N. europaea was able to assimilate up to 70% of the available Fe in the medium even though it is unable to produce siderophores. Addition of exogenous siderophores to Fe-limited medium increased growth (final cell mass). Fe-limited cells had lower heme and cellular Fe contents, reduced membrane layers, and lower NH3- and NH2OH-dependent O2 consumption activities than Fe-replete cells. Fe acquisition-related proteins, such as a number of TonB-dependent Fe-siderophore receptors for ferrichrome and enterobactin and diffusion protein OmpC, were expressed to higher levels under Fe limitation, providing biochemical evidence for adaptation of N. europaea to Fe-limited conditions.
欧洲亚硝化单胞菌作为一种氨氧化细菌，对铁的需求量很高，有90个基因专门用于铁的获取。在铁限制条件（0.2微摩尔铁）下，欧洲亚硝化单胞菌即使不能产生铁载体，也能够吸收培养基中高达70%的可用铁。向铁限制培养基中添加外源铁载体可促进生长（最终细胞量）。与铁充足的细胞相比，铁限制的细胞血红素和细胞铁含量较低，膜层数减少，氨和羟胺依赖的氧气消耗活性较低。在铁限制条件下，一些与铁获取相关的蛋白质，如多种对铁铬素和肠杆菌素具有TonB依赖性的铁载体受体以及扩散蛋白OmpC，表达水平更高，这为欧洲亚硝化单胞菌适应铁限制条件提供了生化证据。
