INRA, UR454 Microbiologie, 63122 Saint-Genès Champanelle, France.
INRA, UR454 Microbiologie, 63122 Saint-Genès Champanelle, France.
Int J Food Microbiol. 2016 May 16;225:20-6. doi: 10.1016/j.ijfoodmicro.2016.03.005. Epub 2016 Mar 8.
Staphylococcus xylosus is frequently isolated from food of animal origin. Moreover, this species is one of the major starter cultures used for meat fermentation. Iron is a key element for growth and survival of bacteria. Meat is particularly rich in haemic (myoglobin and haemoglobin) and non-haemic (ferritin and transferrin) iron sources. Ferritin is a storage protein able to capture large quantities of iron. It is highly resistant to microbial attack and few microorganisms can use it as an iron source. Surprisingly, we found that the S. xylosus C2a strain grows in the presence of ferritin as a sole iron source. A three-cistron operon was highly overexpressed under ferritin iron growth conditions. We generated a deletion-insertion in the first gene of the operon and evaluated the phenotype of the mutant. The mutant showed decreased growth because it was less able to acquire iron from ferritin. Transcriptional analysis of the mutant revealed downregulation of several genes involved in the response to oxidative stress. This study characterized for the first time the capacity of a Staphylococcus to use iron from ferritin and revealed that a potential reductive pathway was involved in this acquisition. We hypothesize that this ability could give an advantage to S. xylosus in meat products.
解木葡萄球菌常从动物源食品中分离出来。此外，该物种是用于肉类发酵的主要发酵剂之一。铁是细菌生长和存活的关键元素。肉类富含血红素（肌红蛋白和血红蛋白）和非血红素（铁蛋白和转铁蛋白）铁源。铁蛋白是一种能够捕获大量铁的储存蛋白。它对微生物的攻击具有高度抗性，很少有微生物可以将其用作铁源。令人惊讶的是，我们发现 S. xylosus C2a 菌株可以在铁蛋白存在的情况下作为唯一的铁源生长。在铁蛋白铁生长条件下，三个顺反子操纵子高度过表达。我们在操纵子的第一个基因中生成了一个缺失-插入，并评估了突变体的表型。由于突变体从铁蛋白中获取铁的能力降低，因此其生长受到影响。对突变体的转录分析显示，参与应对氧化应激的几个基因下调。本研究首次表征了一种葡萄球菌从铁蛋白中获取铁的能力，并揭示了一种潜在的还原途径参与了这种获取。我们假设这种能力可以使 S. xylosus 在肉类产品中具有优势。
