Spatiotemporal Monitoring of the Antibiome Secreted by Bacillus Biofilms on Plant Roots Using MALDI Mass Spectrometry Imaging
Spatiotemporal Monitoring of the Antibiome Secreted by Bacillus Biofilms on Plant Roots Using MALDI Mass Spectrometry Imaging
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DOI：
10.1021/ac500290s
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发表时间：
2014-05-06
影响因子：
7.4
通讯作者：
Ongena, Marc
中科院分区：
文献类型：
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作者：
Debois, Delphine;Jourdan, Emmanuel;Ongena, Marc
一些与植物根系结合的土壤芽孢杆菌可以保护其宿主免受病原微生物的感染，因此正被开发为控制植物疾病的生物制剂。这些细菌的植物保护活性与在实验室条件下作为浮游细胞生长时分泌大量抗生素化合物的潜力有关。然而，这些抗生素在细菌细胞自然定植根组织的根际中的原位表达仍然知之甚少。在这项工作中，我们使用基质辅助激光解吸/电离质谱成像（MALDI MSI）来研究解淀粉芽孢杆菌在根上作为生物膜发育的分泌抗生素组的时空变化。非核糖体脂肽，如植物免疫激发剂表面素或高真菌毒性的iturins和fengycin，很容易产生，尽管在周围培养基中的时间框架和数量不同。有趣的是，直接从凝胶化培养基上进行的串联质谱（MS/MS）实验也使我们能够识别在稍后时间点释放的表面素的新变体。然而，在任何时候都没有检测到其他生物活性化合物，如聚酮类化合物，这强烈表明解淀粉芽孢杆菌在植物中表达的抗生素组并没有反映出用于形成此类化合物的巨大遗传库。这一首次动态研究揭示了MALDI MSI作为鉴定和绘制由根相关细菌合成的抗生素的工具的力量，更广泛地说，在分子水平上研究植物微生物的相互作用。
Some soil Bacilli living in association with plant roots can protect their host from infection by pathogenic microbes and are therefore being developed as biological agents to control plant diseases. The plant-protective activity of these bacteria has been correlated with the potential to secrete a wide array of antibiotic compounds upon growth as planktonic cells in isolated cultures under laboratory conditions. However, in situ expression of these antibiotics in the rhizosphere where bacterial cells naturally colonize root tissues is still poorly understood. In this work, we used matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) to examine spatiotemporal changes in the secreted antibiome of Bacillus amyloliquefaciens developing as biofilms on roots. Nonribosomal lipopeptides such as the plant immunity elicitor surfactin or the highly fungitoxic iturins and fengycins were readily produced albeit in different time frames and quantities in the surrounding medium. Interestingly, tandem mass spectrometry (MS/MS) experiments performed directly from the gelified culture medium also allowed us to identify a new variant of surfactins released at later time points. However, no other bioactive compounds such as polyketides were detected at any time, strongly suggesting that the antibiome expressed in planta by B. amyloliquefaciens does not reflect the vast genetic arsenal devoted to the formation of such compounds. This first dynamic study reveals the power of MALDI MSI as tool to identify and map antibiotics synthesized by root-associated bacteria and, more generally, to investigate plant microbe interactions at the molecular level.