基于直接测量的海洋二固定率翻倍
Tobias Großkopf1, Wiebke Mohr, Tina Baustian
1Helmholtz Centre for Ocean Research Kiel, Kiel, Germany. tgrosskopf@geomar.de
Nature
|August 11, 2012
概括
海洋固对于海洋生产力至关重要. 一种新方法揭示了既定技术低估了固定率,特别是当涉及多种微生物时,这表明全球速度比以前估计的要高.
科学领域:
- 海洋微生物生态学
- 生物地质化学循环 生物地质化学循环
- 海洋学 海洋学 海洋学
背景情况:
- 生物二固化是海洋中的主要来源,调节了初级生产力.
- 目前的估计表明,损失超过固定,造成海洋预算的赤字.
- 已建立的测量海洋N2固定的方法可能无法准确地捕捉到透生物的全部贡献.
研究的目的:
- 将已建立的方法与测量海洋N2固定率的新开发方法进行比较.
- 为了研究如何影响diazotroph社区组成N2固定速率测量.
- 重新评估盆地范围和全球海洋N2固定率.
主要方法:
- 利用分子技术来量化二氧化类群的丰富性.
- 在有机颗粒物中加入15N2的测量速率.
- 通过不同海洋区域的既定和新方法获得的N2固定率进行比较.
主要成果:
- 已确定的方法低估了N2固定率,特别是在Trichodesmium主导的地区 (平均为62%).
- 新方法在单细胞蓝藻细菌和γ-蛋白质细菌占主导地位时,产生了显著更高的N2固定率 (超过六倍).
- 整个大西洋盆地的N2固定率计算为14 ± 1 Tg N yr−1 (既定) 和24 ± 1 Tg N yr−1 (新方法).
结论:
- 隔离体社区的组成显著影响测量的N2固定率.
- 现有的方法可能低估了全球海洋N2固定.
- 全球海洋N2固定率可能远高于先前估计的水平,非Trichodesmium型食菌的贡献更大.
相关概念视频
Inorganic Nitrogen Assimilation
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme nitrate reductase...
Carbon-dioxide Fixation
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...
Microbial Growth Measurement: Direct Methods
Direct methods for measuring microbial populations in a culture are essential tools in microbiology, providing quantitative data for various applications. Among these, microscopic counts, plate counts, and serial dilution are widely used techniques, each with unique principles and applications.Microscopic CountsMicroscopic counting involves the use of a Petroff-Hausser chamber, a specialized microscope slide with a grid and defined depth. By observing a liquid culture under a microscope,...
Microbial Growth Measurement: Indirect Methods
Estimating microbial growth is essential for understanding population dynamics and environmental adaptations. Indirect methods provide valuable insights by measuring parameters such as turbidity, metabolic activity, and biomass, enabling efficient and reproducible assessments.During exponential growth, microbial cells scatter light proportionally to their biomass, a principle used in turbidity measurements. About one million cells per milliliter produce detectable scattering, which a...
The Calvin Benson Cycle
Ribulose 1,5- bisphosphate carboxylase/oxygenase (RuBisCo) is a critical enzyme that catalyzes carbon dioxide assimilation during photosynthesis. However, it is an inefficient enzyme, having an extremely slow catalytic rate. A typical enzyme can process about a thousand molecules per second; however, RuBisCo fixes only around three-carbon dioxides per second. Photosynthetic cells compensate for this slow rate by synthesizing very high amounts of RuBisCo, making it the most abundant single...
Overview of Nitrogen Metabolism
Nitrogen is a very important element for life because it is a major constituent of proteins and nucleic acids. It is a macronutrient, and in nature, it is recycled from organic compounds and stored in the form of ammonia, ammonium ions, nitrate, nitrite, or nitrogen gas by many metabolic processes. Many of these metabolic processes are carried out only by prokaryotes.
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this nitrogen...
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this nitrogen...


