Bethke J, Poblete-Morales M, Irgang R, Yáñez A, Avendaño-Herrera R
Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Viña del Mar, Chile.
Interdisciplinary Center for Aquaculture Research (INCAR), Concepción, Chile.
J Fish Dis. 2016 Nov;39(11):1275-1283. doi: 10.1111/jfd.12456. Epub 2016 Jan 27.
Renibacterium salmoninarum is the causative agent of bacterial kidney disease, which significantly affects salmonid farming worldwide. Despite this impact, there is scarce data on its iron uptake ability, a factor of pathogenesis. This study investigated the iron acquisition mechanisms of R. salmoninarum and its capacity to uptake iron from different sources. Thirty-two Chilean isolates and the DSM20767 type strain grew in the presence of 2,2'-Dipyridyl at varying concentrations (250-330 μm), and all isolates positively reacted on chrome azurol S agar. Subsequently, inocula of four Chilean isolates and the type strain were prepared with or without 200 μm of 2,2'-Dipyridyl for uptake assays. Assay results revealed differences between the isolates in terms of iron acquisition. While a prior iron-limited environment was, for most isolates, not required to activate the uptake of iron (II) sulphate, ammonium iron (III) citrate or iron (III) chloride at higher concentrations (100 μm), it did facilitate growth at lower iron concentrations (10 μm and 1 μm). An exception was the H-2 isolate, which only grew with 100 μm of iron sulphide. In turn, 100 μm of haemin was toxic when isolates were grown in normal KDM-2. In silico R. salmoninarumATCC 33209 genome analysis detected various genes coding iron uptake-related proteins. This is the first study indicating two iron acquisition systems in R. salmoninarum: one involving siderophores and another involving haem group utilization. These data represent a first step towards fully elucidating this virulence factor in the pathogenic R. salmoninarum.
鲑肾杆菌是细菌性肾病的病原体，对全球鲑科鱼类养殖造成重大影响。尽管有此影响，但关于其铁摄取能力（发病机制的一个因素）的数据却很少。本研究调查了鲑肾杆菌的铁获取机制及其从不同来源摄取铁的能力。32株智利分离株和DSM20767模式菌株在不同浓度（250 - 330μm）的2,2'-联吡啶存在下生长，并且所有分离株在铬天青S琼脂上呈阳性反应。随后，制备了四株智利分离株和模式菌株的接种物，分别添加或不添加200μm的2,2'-联吡啶用于摄取试验。试验结果显示各分离株在铁获取方面存在差异。虽然对于大多数分离株来说，在较高浓度（100μm）下摄取硫酸亚铁、柠檬酸铁铵或氯化铁（III）时，不需要预先的铁限制环境来激活铁摄取，但在较低铁浓度（10μm和1μm）下，铁限制环境确实促进了生长。例外的是H - 2分离株，它仅在100μm的硫化铁存在下生长。反过来，当分离株在正常的KDM - 2中生长时，100μm的血红素是有毒的。对鲑肾杆菌ATCC 33209基因组进行的电子分析检测到了各种编码铁摄取相关蛋白的基因。这是第一项表明鲑肾杆菌存在两种铁获取系统的研究：一种涉及铁载体，另一种涉及血红素基团利用。这些数据代表了朝着全面阐明致病性鲑肾杆菌中这种毒力因子迈出的第一步。
