Nitrate respiration and diel migration patterns of diatoms are linked in sediments underneath a microbial mat
Nitrate respiration and diel migration patterns of diatoms are linked in sediments underneath a microbial mat
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硅藻的硝酸盐呼吸和昼夜迁移模式与微生物垫下的沉积物有关
DOI：
10.1111/1462-2920.15345
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发表时间：
2020
影响因子：
5.1
通讯作者：
Marchant, Hannah K.
中科院分区：
文献类型：
--
作者：
Merz, Elisa;Dick, Gregory J.;de Beer, Dirk;Grim, Sharon;Hübener, Thomas;Littmann, Sten;Olsen, Kirk;Stuart, Dack;Lavik, Gaute;Marchant, Hannah K.
硅藻是少数几种已知的储存硝酸盐（NO3−）的真核生物之一，并在没有光和O2的情况下将其用作呼吸的电子受体。利用显微镜和15 N稳定同位素培养，我们研究了异化硝酸盐/亚硝酸盐还原为铵（DNRA）和硅藻在光合微生物垫和下面的沉积物的天坑在休伦湖（美国）的昼夜垂直迁移之间的关系。我们发现，硅藻在下午在垫-水界面迅速积累NO3−，40%的种群迁移到沉积物深处，在那里它们暴露在黑暗和缺氧条件下约75%的时间。DNRA速率的垂直分布与硅藻丰度最大值相吻合，表明DNRA是硅藻种群的主要能量代谢。我们的结论是，照明氧化还原动力学生态系统选择迁移硅藻，可以在没有光的情况下储存硝酸盐进行呼吸。这项研究的一个主要含义是，DNRA对反硝化的优势不是由动力学或热力学解释。相反，动态条件选择迁移硅藻执行DNRA，可以胜过固着的硅藻。
Diatoms are among the few eukaryotes known to store nitrate (NO3−) and to use it as an electron acceptor for respiration in the absence of light and O2. Using microscopy and15N stable isotope incubations, we studied the relationship between dissimilatory nitrate/nitrite reduction to ammonium (DNRA) and diel vertical migration of diatoms in phototrophic microbial mats and the underlying sediment of a sinkhole in Lake Huron (USA). We found that the diatoms rapidly accumulated NO3−at the mat‐water interface in the afternoon and 40% of the population migrated deep into the sediment, where they were exposed to dark and anoxic conditions for ~75% of the day. The vertical distribution of DNRA rates and diatom abundance maxima coincided, suggesting that DNRA was the main energy generating metabolism of the diatom population. We conclude that the illuminated redox‐dynamic ecosystem selects for migratory diatoms that can store nitrate for respiration in the absence of light. A major implication of this study is that the dominance of DNRA over denitrification is not explained by kinetics or thermodynamics. Rather, the dynamic conditions select for migratory diatoms that perform DNRA and can outcompete sessile denitrifiers.