Collaborative Research: Unraveling Patterns of Infection and Co-Speciation among Earthworm-Bacterial Symbiont Associations

蚯蚓是最知名的土居动物之一，除了南极洲，在每个大陆都有。 它们在改变土壤结构和全世界土壤中的养分供应方面很活跃，并以其在堆肥中的效用而闻名。 蚯蚓在其内部肾状器官肾管（英语：nephridia）（英语：200每蠕虫），消除废液（“尿”）。 与肠道的多样性微生物群不同，肾管的细菌似乎形成稳定和特定的关联，使得特定种类的蚯蚓拥有自己的共生噬酸菌。 此外，最近在赤子爱氏菌中发现了与放线菌有关的第二种细菌共生体，这表明放线菌共生体之间的多样性更大。 细菌的多样性与不同的亚门分类群和他们的贡献，蚯蚓的成功，几乎是未开发的。 这项合作研究项目整合了形态鉴定和基因序列信息，以鉴定来自几个大陆的蚯蚓及其相关共生细菌。 一组在确定生物体之间关系方面取得成功的基因已被选择进行测序。 这些数据将用于确定宿主蚯蚓及其细菌伴侣之间的遗传关系，以建立这种关联的进化模式。 新物种的宿主和共生体的发现，以及更好地了解蚯蚓及其相关的细菌的多样性。 这项研究对于了解土壤中发生的过程至关重要，这些过程通过土壤系统中这些广泛存在的成员的活动影响土壤化学和肥力。 此外，共生细菌谱系之一可能是新的抗微生物化合物的来源。 蚯蚓的多样性和全球分布为细菌共生体的进化提供了机会，并有可能产生新的生物活性化合物和酶。国际合作是研究的必要组成部分，以完成从几个大陆的收集，并有助于国际努力积累用于快速生物识别的序列（“生命条形码”）。这项工作将吸引年轻科学家参与，并为他们提供实地收集、系统发生学分子方法和细菌群落分析方面的培训。

Earthworms are among the most recognized soil-dwelling animals and occur on every continent except Antarctica. They are active in altering soil structure and nutrient availability in soils throughout the world, and known for their utility in composting. Earthworms harbor symbiotic bacteria of the Acidovorax genus in their internal kidney-like organs, the nephridia (ca. 200 per worm), that eliminate waste fluid ("urine"). Unlike the diverse microbiota of the gut, bacteria of the nephridia appear to form stable and specific associations such that particular species of earthworms harbor their own species of symbiotic Acidovorax. In addition, a second bacterial symbiont related to Actinobacteria was recently discovered in Eisenia fetida, suggesting even greater diversity among earthworm symbionts. The diversity of the bacteria associated with different earthworm taxa and their contribution to the success of earthworms are virtually unexplored. This collaborative research project integrates morphological identification and genetic sequence information to identify earthworms and their associated symbiotic bacteria from several continents. A suite of genes that have shown previous success in determining relationships among organisms has been selected to be sequenced. The data will be used to determine the genetic relationships among both the host earthworms and their bacterial partners to establish evolutionary patterns for this association. Discovery of novel species of both the host and symbiont is expected as well as a better understanding of the diversity of the earthworms and their associated bacteria. This research is crucial for understanding the processes occurring in the soil that influence soil chemistry and fertility through the activity of these widespread members of soil systems. Furthermore, one of the symbiotic bacterial lineages may be a source of novel anti-microbial compounds. The diversity and global distribution of earthworms offers an opportunity for the evolution of bacterial symbionts with potential for new bioactive compounds and enzymes.International collaborations are a necessary part of the research to accomplish collections from several continents and contribute to an international effort to accumulate sequences for rapid organism identification ("BarCode of Life"). The work will engage and provide training to young scientists in field collection, molecular methods for phylogenetic systematics and bacterial community analysis.