研究人员利用大陆尺度的宏基因组学来证明淡水系统中的氨氧化古菌物种多样性比海洋环境低。研究发现，1300万年前，未培养的淡水氨氧化古菌，命名为“Candidatthem Nitrosopumilthem limneticthem”，在各种大型欧洲湖泊中无处不在，且基因型稳定。研究结果强调，广泛的蛋白质组改造是淡水定植氨氧化古菌的关键创新。这些发现揭示了湖泊中克隆生存了数千年的关键物种的遗传多样性和适应机制。
据悉，氨氧化古菌(AOA)在水体氮循环中起着关键作用。它们的遗传多样性被认为是形成祖先从陆地栖息地向海洋栖息地过渡的进化过程的结果。然而，目前对氨氧化古菌进化的全基因组研究很少考虑微咸水和淡水的代表，也很少提供它们在湖泊系统中的分化时间线。对湖泊中的氨氧化古菌多样性进行无偏见的全球评估对于了解其起源、扩散机制和生态系统作用至关重要。
附：英文原文
Title: Postglacial adaptations enabled colonization and quasi-clonal dispersal of ammonia-oxidizing archaea in modern European large lakes
Author: David Kamanda Ngugi, Michaela M. Salcher, Adrian-Stefan Andrei, Rohit Ghai, Franziska Klotz, Maria-Cecilia Chiriac, Danny Ionescu, Petra Büsing, Hans-Peter Grossart, Peng Xing, John C. Priscu, Salmor Alymkulov, Michael Pester
Issue&Volume: 2023-02-01
Abstract: Ammonia-oxidizing archaea (AOA) play a key role in the aquatic nitrogen cycle. Their genetic diversity is viewed as the outcome of evolutionary processes that shaped ancestral transition from terrestrial to marine habitats. However, current genome-wide insights into AOA evolution rarely consider brackish and freshwater representatives or provide their divergence timeline in lacustrine systems. An unbiased global assessment of lacustrine AOA diversity is critical for understanding their origins, dispersal mechanisms, and ecosystem roles. Here, we leveraged continental-scale metagenomics to document that AOA species diversity in freshwater systems is remarkably low compared to marine environments. We show that the uncultured freshwater AOA, “Candidatus Nitrosopumilus limneticus,” is ubiquitous and genotypically static in various large European lakes where it evolved 13 million years ago. We find that extensive proteome remodeling was a key innovation for freshwater colonization of AOA. These findings reveal the genetic diversity and adaptive mechanisms of a keystone species that has survived clonally in lakes for millennia.
DOI: adc9392
Source: https://www.science.org/doi/10.1126/sciadv.adc9392