Institute of Environmental Research (INFU), Department of Chemistry and Chemical Biology, Chair of Environmental Chemistry and Analytical Chemistry, TU Dortmund , Otto-Hahn-Straße 6, D-44221 Dortmund, Germany.
J Nat Prod. 2014 Dec 26;77(12):2577-84. doi: 10.1021/np500219a. Epub 2014 Dec 5.
Several recent studies have lent evidence to the fact that certain so-called plant metabolites are actually biosynthesized by associated microorganisms. In this work, we show that the original source organism(s) responsible for the biosynthesis of the important anticancer and cytotoxic compound maytansine is the endophytic bacterial community harbored specifically within the roots of Putterlickia verrucosa and P. retrospinosa plants. Evaluation of the root endophytic community by chemical characterization of their fermentation products using HPLC-HRMS(n), along with a selective microbiological assay using the maytansine-sensitive type strain Hamigera avellanea revealed the endophytic production of maytansine. This was further confirmed by the presence of AHBA synthase genes in the root endophytic communities. Finally, MALDI-imaging-HRMS was used to demonstrate that maytansine produced by the endophytes is typically accumulated mainly in the root cortex of both plants. Our study, thus, reveals that maytansine is actually a biosynthetic product of root-associated endophytic microorganisms. The knowledge gained from this study provides fundamental insights on the biosynthesis of so-called plant metabolites by endophytes residing in distinct ecological niches.
某些所谓的植物代谢物实际上是由相关微生物生物合成的。在这项工作中，我们表明，负责生物合成重要抗癌和细胞毒性化合物美登素的原始源生物体是内生细菌群落，它们专门存在于 Putterlickia verrucosa 和 P. retrospinosa 植物的根部。通过使用 HPLC-HRMS(n)对其发酵产物进行化学特征分析，以及使用对美登素敏感的模式菌株 Hamigera avellanea 进行选择性微生物测定，评估根内生群落，发现内生菌产生了美登素。根内生群落中存在 AHBA 合酶基因进一步证实了这一点。最后，使用 MALDI-成像-HRMS 证明内生菌产生的美登素主要积累在这两种植物的根皮层中。因此，我们的研究表明，美登素实际上是根相关内生微生物的生物合成产物。从这项研究中获得的知识为内生菌在不同生态位中合成所谓的植物代谢物提供了基本的见解。
