Potential competition between marine heterotrophic prokaryotes and autotrophic picoplankton for nitrogen substrates
Potential competition between marine heterotrophic prokaryotes and autotrophic picoplankton for nitrogen substrates
复制标题
海洋异养原核生物和自养超微型浮游生物之间对氮底物的潜在竞争
DOI：
10.1002/lno.11883
复制
发表时间：
2021-06-30
影响因子：
4.5
通讯作者：
Zhang, Yao
中科院分区：
文献类型：
--
作者：
Deng, Wenchao;Wang, Shanlin;Zhang, Yao
异养原核生物具有吸收无机氮（N）底物的能力。然而，目前还不清楚异养原核生物和自养浮游生物之间的潜在竞争是什么N在海洋中，这将分流的N流支持初级生产。到目前为止，它一直很难区分异养原核生物的N吸收的自养微型浮游生物，特别是在贫营养的海洋蓝藻为主。我们进行了现场为基础的DNA稳定同位素探测孵化实验在中国南海相结合的测量铵，硝酸盐，亚硝酸盐和尿素的吸收速率，以估计分类特定的潜在N同化。结果表明，在中国南海大陆架真光层和开阔海域，具有不同遗传多样性的异养原核生物具有显著的多氮源吸收能力，分别占总氮吸收潜力的17-41%和19-55%，与蓝藻（主要是原绿球藻）存在潜在的竞争关系。值得注意的是，异养原核生物作出了更高的贡献，大量吸收硝酸盐的孵育系统中的开放的海洋相对于再生N，因此有一种倾向，高估的F-比率。通过全球模型将我们的结果外推到贫营养的低纬度海洋，表明f-比率将下降18%。这表明一个更复杂的生态地球化学作用的异养原核生物在生物碳泵比迄今为止假设，在广阔的开放海洋中的N和碳循环的重要影响。
Heterotrophic prokaryotes have the capacity to uptake inorganic nitrogen (N) substrates. However, it remains unclear what the potential competition is between heterotrophic prokaryotes and autotrophic plankton for N in the ocean, which would shunt the flow of N supporting primary production. To date, it has been difficult to distinguish heterotrophic prokaryotic N uptake from that of autotrophic picoplankton, especially in oligotrophic oceans dominated by cyanobacteria. We carried out field-based DNA stable isotope probing incubation experiments in the South China Sea combining measurements of uptake rates of ammonium, nitrate, nitrite, and urea to estimate the taxon-specific potential N assimilation. The results indicate that phylogenetically diverse heterotrophic prokaryotes significantly incorporated multiple N sources, contributing approximately 17-41% and 19-55% of total N uptake potential in the euphotic zone of the South China Sea continental shelf and open ocean, respectively, potentially competing with cyanobacteria (mainly Prochlorococcus). Notably, heterotrophic prokaryotes made a higher contribution to bulk uptake of nitrate in the incubation systems of the open ocean relative to regenerated N, and thus there was a tendency to overestimate the f-ratio. Extrapolating our results to the oligotrophic, low-latitude ocean via a global model suggests the f-ratio would decrease similar to 18%. This suggests a more complicated biogeochemical role of heterotrophic prokaryotes in the biological carbon pump than hitherto assumed, with important implications for N and carbon cycling in the vast open ocean.