The plant microbiome is a vastly underutilized resource for identifying new genes and bioactive compounds. Here, we used Pseudomonas sp. EDOX, isolated from the leaf endosphere of a tomato plant grown on a small farm in the Netherlands. To get more insight into its biosynthetic potential, the genome of Pseudomonas sp. EDOX was sequenced and subjected to bioinformatic analyses. The genome sequencing analysis identified strain EDOX as a member of the Pseudomonas mediterranea. In silico analysis for secondary metabolites identified a total of five non-ribosomally synthesized peptides synthetase (NRPS) gene clusters, related to the biosynthesis of syringomycin, syringopeptin, anikasin, crochelin A, and fragin. Subsequently, we purified and characterized several cyclic lipopeptides (CLPs) produced by NRPS, including some of the already known ones, which have biological activity against several plant and human pathogens. Most notably, mass spectrometric analysis led to the discovery of two yet unknown CLPs, designated medipeptins, consisting of a 22 amino acid peptide moiety with varying degrees of activity against Gram-positive and Gram-negative pathogens. Furthermore, we investigated the mode of action of medipeptin A. The results show that medipeptin A acts as a bactericidal antibiotic against Gram-positive pathogens, but as a bacteriostatic antibiotic against Gram-negative pathogens. Medipeptin A exerts its potent antimicrobial activity against Gram-positive bacteria via binding to both lipoteichoic acid (LTA) and lipid II as well as by forming pores in membranes. Collectively, our study provides important insights into the biosynthesis and mode of action of these novel medipeptins from P. mediterranea EDOX.

植物微生物组是一种未充分利用的资源，用于识别新基因和生物活性化合物。在这里，我们使用了假单胞菌属sp。EDOX，从荷兰一个小农场种植的番茄植株的叶内层中分离出来。为了更深入地了解其生物合成潜力，假单胞菌属sp。EDOX 被测序并进行生物信息学分析。基因组测序分析确定 EDOX 菌株为地中海假单胞菌。计算机模拟对次生代谢物的分析总共鉴定了 5 个非核糖体合成肽合成酶 (NRPS) 基因簇，与丁香​​霉素、丁香肽、阿尼卡星、crochelin A 和 fragin 的生物合成相关。随后，我们纯化并表征了 NRPS 产生的几种环状脂肽（CLP），包括一些已知的脂肽，它们对多种植物和人类病原体具有生物活性。最值得注意的是，质谱分析发现了两种未知的 CLP，称为 medipeptins，由 22 个氨基酸肽部分组成，对革兰氏阳性和革兰氏阴性病原体具有不同程度的活性。此外，我们研究了medipeptin A的作用方式。结果表明，medipeptin A作为针对革兰氏阳性病原体的杀菌抗生素，但作为针对革兰氏阴性病原体的抑菌抗生素。Medipeptin A 对革兰氏阳性菌发挥有效的抗菌活性通过与脂磷壁酸 (LTA) 和脂质 II 结合以及在膜上形成孔。总的来说，我们的研究为这些新型 medieptins 的生物合成和作用模式提供了重要的见解。地中海松EDOX。