The Siderophore Product Ornibactin Is Required for the Bactericidal Activity of Burkholderia contaminans MS14
The Siderophore Product Ornibactin Is Required for the Bactericidal Activity of Burkholderia contaminans MS14
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DOI：
10.1128/aem.00051-17
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发表时间：
2017-04-01
影响因子：
4.4
通讯作者：
Lu, Shi-En
中科院分区：
文献类型：
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作者：
Deng, Peng;Foxfire, Adam;Lu, Shi-En
污染伯克霍尔德氏菌MS 14从密西西比的土壤中分离。当它在营养肉汤-酵母提取物琼脂上培养时，菌落对广泛的植物病原菌表现出杀菌活性。一种具有铁载体活性的抑菌化合物被成功地纯化，并通过核磁共振光谱确定为鸟杆菌素。尚未实现杀菌化合物的分离;因此，杀菌化合物的确切性质仍然未知。在尝试分离杀菌化合物的过程中，表征了Ornibactin的产生与MS 14的杀菌活性之间的有趣关系。转座子诱变导致两种菌株失去杀菌活性，在非核糖体肽合成酶（NRPS）基因的鸟杆菌素生物合成和luxR家族转录调控基因的插入突变。这两种突变菌株的共培养导致杀菌活性的恢复。此外，添加Ornibactin到NRPS突变体恢复了杀菌表型。已经证明，在MS 14中，除了铁螯合之外，奥奈菌素具有替代功能。在伯克霍尔德氏菌属物种的鸟杆菌素生物合成基因的比较显示的调控元件之间的多样性，而鸟杆菌素合成的基因产物是保守的。这是一个有趣的观察结果，因为鸟杆菌素被认为在伯克霍尔德氏菌属物种中具有相同的定义功能。Ornibactin是由大多数伯克霍尔德氏菌属物种产生的，它在调节次级代谢产物产生中的作用应该被调查。重要性从菌株MS 14中鉴定抗菌产物不是本研究的关键特征。我们提出了一系列的实验，证明了Ornibactin是直接参与杀菌表型的MS 14。这一观察结果提供了证据，除了铁螯合，鸟杆菌素的替代功能。Ornibactin应进一步评估其在调节其他伯克霍尔德菌属物种次生代谢产物生物合成中的作用。
Burkholderia contaminans MS14 was isolated from soil in Mississippi. When it is cultivated on nutrient broth-yeast extract agar, the colonies exhibit bactericidal activity against a wide range of plant-pathogenic bacteria. A bacteriostatic compound with siderophore activity was successfully purified and was determined by nuclear magnetic resonance spectroscopy to be ornibactin. Isolation of the bactericidal compound has not yet been achieved; therefore, the exact nature of the bactericidal compound is still unknown. During an attempt to isolate the bactericidal compound, an interesting relationship between the production of ornibactin and the bactericidal activity of MS14 was characterized. Transposon mutagenesis resulted in two strains that lost bactericidal activity, with insertional mutations in a nonribosomal peptide synthetase (NRPS) gene for ornibactin biosynthesis and a luxR family transcriptional regulatory gene. Coculture of these two mutant strains resulted in restoration of the bactericidal activity. Furthermore, the addition of ornibactin to the NRPS mutant restored the bactericidal phenotype. It has been demonstrated that, in MS14, ornibactin has an alternative function, aside from iron sequestration. Comparison of the ornibactin biosynthesis genes in Burkholderia species shows diversity among the regulatory elements, while the gene products for ornibactin synthesis are conserved. This is an interesting observation, given that ornibactin is thought to have the same defined function within Burkholderia species. Ornibactin is produced by most Burkholderia species, and its role in regulating the production of secondary metabolites should be investigated.IMPORTANCE Identification of the antibacterial product from strain MS14 is not the key feature of this study. We present a series of experiments that demonstrate that ornibactin is directly involved in the bactericidal phenotype of MS14. This observation provides evidence for an alternative function for ornibactin, aside from iron sequestration. Ornibactin should be further evaluated for its role in regulating the biosynthesis of secondary metabolites in other Burkholderia species.