美国伍兹霍尔海洋研究所Repeta, Daniel J.团队，近日在研究海洋边缘地带的微生物铁限制中取得新进展。相关论文发表在2024年9月25日出版的《自然》杂志上。

据研究人员介绍，受阳光照射的表层海洋的初级生产受到关键营养物质——主要是硝酸盐、磷酸盐和铁(Fe)供应的调节，浮游植物需要这些营养物质将二氧化碳固定在生物物质中。在海洋表面以下，下沉的有机物的再矿化作用迅速再生营养物质，中上层“过渡带”(200-500米)的微生物代谢被认为受到不稳定有机碳输送的限制。然而，很少有研究检验营养物质在塑造中层微生物生产中的作用。

该研究展示了铁载体的分布和吸收，铁载体是横跨东太平洋的子午线断面微生物贫铁的生物标志物。铁载体的浓度不仅在长期受铁限制的表层水中含量很高，而且在南北太平洋亚热带环流(两个海洋碳循环的关键生态系统)下面的过渡带中也很高。研究结果表明，由于铁可用性低而导致的细菌铁缺乏，可能是几个大型海洋盆地的过渡带的特征，极大地扩大了海洋水柱的区域，其中营养物质限制了微生物的代谢，这对海洋碳储存有潜在的影响。

附：英文原文

Title: Microbial iron limitation in the ocean’s twilight zone

Author: Li, Jingxuan, Babcock-Adams, Lydia, Boiteau, Rene M., McIlvin, Matthew R., Manck, Lauren E., Sieber, Matthias, Lanning, Nathan T., Bundy, Randelle M., Bian, Xiaopeng, treang, Iulia-Mdlina, Granzow, Benjamin N., Church, Matthew J., Fitzsimmons, Jessica N., John, Seth G., Conway, Tim M., Repeta, Daniel J.

Issue&Volume: 2024-09-25

Abstract: Primary production in the sunlit surface ocean is regulated by the supply of key nutrients, primarily nitrate, phosphate and iron (Fe), required by phytoplankton to fix carbon dioxide into biomass. Below the surface ocean, remineralization of sinking organic matter rapidly regenerates nutrients, and microbial metabolism in the upper mesopelagic ‘twilight zone’ (200–500m) is thought to be limited by the delivery of labile organic carbon. However, few studies have examined the role of nutrients in shaping microbial production in the mesopelagic. Here we report the distribution and uptake of siderophores, biomarkers for microbial Fe deficiency across a meridional section of the eastern Pacific Ocean. Siderophore concentrations are high not only in chronically Fe-limited surface waters but also in the twilight zone underlying the North and South Pacific subtropical gyres, two key ecosystems for the marine carbon cycle. Our findings suggest that bacterial Fe deficiency owing to low Fe availability is probably characteristic of the twilight zone in several large ocean basins, greatly expanding the region of the marine water column in which nutrients limit microbial metabolism, with potential implications for ocean carbon storage.

DOI: 10.1038/s41586-024-07905-z

Source: https://www.nature.com/articles/s41586-024-07905-z