Ammonia-oxidizing archaea release a suite of organic compounds potentially fueling prokaryotic heterotrophy in the ocean
Ammonia-oxidizing archaea release a suite of organic compounds potentially fueling prokaryotic heterotrophy in the ocean
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DOI：
10.1111/1462-2920.14755
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发表时间：
2019-08-06
影响因子：
5.1
通讯作者：
Herndl, Gerhard J.
中科院分区：
文献类型：
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作者：
Bayer, Barbara;Hansman, Roberta L.;Herndl, Gerhard J.
氨氧化古菌 (AOA) 构成了全球海洋微生物量的相当一部分，占海洋原核浮游生物的 20%-40%。然而，这些化能自养古菌释放溶解有机碳（DOC）的程度仍然是个谜。结合靶向和非靶向代谢组学来表征 Nitrosopumilus 属的三种 AOA 模型菌株的外代谢组。我们的结果表明，海洋 AOA 散发出一系列具有潜在不同反应性的有机化合物，其中以含氮化合物为主。释放的溶解有机物 (DOM) 的很大一部分由不稳定化合物组成，这些化合物通常限制公海水域中的原核生物异养活性，包括氨基酸、胸苷和 B 族维生素。氨基酸释放速率与氨氧化活性相对应，三种 Nitrosopumilus 菌株主要释放疏水性氨基酸，可能是被动扩散的结果。尽管 AOA 释放的 DOC 对异养原核生物碳需求的贡献较低（大约为 0.08%-1.05%），但生理相关代谢物的释放对于其中一些化合物的营养缺陷型微生物（包括全球丰富且普遍存在的 SAR11 进化枝的成员）可能至关重要。
Ammonia-oxidizing archaea (AOA) constitute a considerable fraction of microbial biomass in the global ocean, comprising 20%-40% of the ocean's prokaryotic plankton. However, it remains enigmatic to what extent these chemolithoautotrophic archaea release dissolved organic carbon (DOC). A combination of targeted and untargeted metabolomics was used to characterize the exometabolomes of three model AOA strains of the Nitrosopumilus genus. Our results indicate that marine AOA exude a suite of organic compounds with potentially varying reactivities, dominated by nitrogen-containing compounds. A significant fraction of the released dissolved organic matter (DOM) consists of labile compounds, which typically limit prokaryotic heterotrophic activity in open ocean waters, including amino acids, thymidine and B vitamins. Amino acid release rates corresponded with ammonia oxidation activity and the three Nitrosopumilus strains predominantly released hydrophobic amino acids, potentially as a result of passive diffusion. Despite the low contribution of DOC released by AOA (similar to 0.08%-1.05%) to the heterotrophic prokaryotic carbon demand, the release of physiologically relevant metabolites could be crucial for microbes that are auxotrophic for some of these compounds, including members of the globally abundant and ubiquitous SAR11 clade.