Delmotte Nathanaël, Knief Claudia, Chaffron Samuel, Innerebner Gerd, Roschitzki Bernd, Schlapbach Ralph, von Mering Christian, Vorholt Julia A
Institute of Microbiology, Eidgenössische Technische Hochschule Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland.
Proc Natl Acad Sci U S A. 2009 Sep 22;106(38):16428-33. doi: 10.1073/pnas.0905240106. Epub 2009 Sep 4.
Aerial plant surfaces represent the largest biological interface on Earth and provide essential services as sites of carbon dioxide fixation, molecular oxygen release, and primary biomass production. Rather than existing as axenic organisms, plants are colonized by microorganisms that affect both their health and growth. To gain insight into the physiology of phyllosphere bacteria under in situ conditions, we performed a culture-independent analysis of the microbiota associated with leaves of soybean, clover, and Arabidopsis thaliana plants using a metaproteogenomic approach. We found a high consistency of the communities on the 3 different plant species, both with respect to the predominant community members (including the alphaproteobacterial genera Sphingomonas and Methylo bacterium) and with respect to their proteomes. Observed known proteins of Methylobacterium were to a large extent related to the ability of these bacteria to use methanol as a source of carbon and energy. A remarkably high expression of various TonB-dependent receptors was observed for Sphingomonas. Because these outer membrane proteins are involved in transport processes of various carbohydrates, a particularly large substrate utilization pattern for Sphingomonads can be assumed to occur in the phyllosphere. These adaptations at the genus level can be expected to contribute to the success and coexistence of these 2 taxa on plant leaves. We anticipate that our results will form the basis for the identification of unique traits of phyllosphere bacteria, and for uncovering previously unrecorded mechanisms of bacteria-plant and bacteria-bacteria relationships.
气生植物表面是地球上最大的生物界面，作为二氧化碳固定、分子氧释放和初级生物质生产的场所，提供着重要服务。植物并非以无菌生物的形式存在，而是被影响其健康和生长的微生物所定殖。为深入了解原位条件下叶际细菌的生理学，我们采用宏蛋白质基因组学方法，对与大豆、三叶草和拟南芥叶片相关的微生物群进行了非培养分析。我们发现，这3种不同植物物种上的群落，在主要群落成员（包括α-变形菌属的鞘氨醇单胞菌属和甲基杆菌属）及其蛋白质组方面都具有高度一致性。观察到甲基杆菌的已知蛋白质在很大程度上与这些细菌利用甲醇作为碳源和能源的能力有关。鞘氨醇单胞菌中观察到各种TonB依赖性受体的表达显著较高。由于这些外膜蛋白参与各种碳水化合物的运输过程，可以推测鞘氨醇单胞菌在叶际具有特别大的底物利用模式。这些属水平的适应性变化有望促进这两个分类群在植物叶片上的成功定殖和共存。我们预计，我们的研究结果将为识别叶际细菌的独特特征以及揭示以前未记录的细菌与植物、细菌与细菌之间的关系机制奠定基础。
