Study of the impact of anthropogenic stress on frankia sp., alders, and their symbiosis

Frankia属的丝状放线菌普遍存在，并在全球固氮中发挥重要作用。它们与宿主植物（放线根植物，其中包括桤木）建立了类似于豆科植物与根瘤菌的根瘤共生关系。在北美，赤杨因其分布、健壮性和对各种恶劣环境条件的适应性而特别受关注。虽然放线菌的桤木通常用于植被恢复的土地（如含金属的矿山废物），很少有研究集中在人为污染物（重金属，环烷酸，氯代芳烃）如何影响放线菌共生。这些问题是更重要的考虑frankiae，在其sacrobitic生命周期，直接暴露于这些土壤污染物。

Filamentous actinobacteria of the genus Frankia are ubiquitous and participate significantly in global nitrogen fixation. With their host plants (actinorhizal plants, amongst which alders), they establish a root nodule symbiosis analogous to that of legumes with rhizobia. In North America, alders are of particular interest for their distribution, robustness and adaptation to a wide range of harsh environmental conditions. Although actinorhizal alders are routinely used for the revegetation of derelict lands (e.g. metalliferous mine wastes), little research has focussed on how anthropogenic contaminants (heavy metals, naphtenic acids, and chloroaromatic hydrocarbons) affect the actinorhizal symbiosis. These questions are even more important considering that frankiae, in their saprophytic life cycle, are directly exposed to these soil contaminants.