Lipid biosynthesis of Nitrosopumilus maritimus dissected by lipid specific radioisotope probing (lipid-RIP) under contrasting ammonium supply
Lipid biosynthesis of Nitrosopumilus maritimus dissected by lipid specific radioisotope probing (lipid-RIP) under contrasting ammonium supply
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DOI：
10.1016/j.gca.2018.09.001
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发表时间：
2018-12
影响因子：
5
通讯作者：
T. Evans;M. Könneke;J. Lipp;R. Adhikari;H. Taubner;M. Elvert;K. Hinrichs
中科院分区：
文献类型：
--
作者：
T. Evans;M. Könneke;J. Lipp;R. Adhikari;H. Taubner;M. Elvert;K. Hinrichs
氨氧化古菌（AOA）是海洋中最丰富的微生物之一，是水柱和底层沉积物中甘油二联植烷基甘油四醚（GDGT）的主要来源之一。然而，很少有人知道的GDGT生物合成过程中的机械步骤，形成的TEX 86古温度计的基础。最近的研究表明，除了温度，生理因素，如生长阶段和铵氧化速率的变化可能会影响TEX 86温度代理。我们用放射性标记的14 C-碳酸氢盐进行了短期孵育实验，以准确追踪高和低铵（NH 4+）供应对AOA模型生物Nitrosopumilus maritimus产生单个膜脂质的影响。在生长过程中的14 C掺入监测在5个时间间隔的液相色谱法耦合到流过闪烁计数的水解膜脂质提取物，允许一个简单的和敏感的在线检测of 14 C掺入到古细菌脂质的时间尺度低于一个单一的细胞周期。实验表明，低NH 4+供应导致GDGT的更高的环化，优先合成crenarchaeol，而过量NH 4+导致GDGT-0的主要生产。因此，使用TEX 86 L校准，具有高NH 4+供应的培养物导致比具有低量可用NH 4+的培养物低高达10 °C的估计孵育温度。有趣的是，在所有实验开始时观察到高的古菌相对产量（高达27%），与NH 4+供应无关;同样，环化程度最初最低，表明延迟产生环烷基化衍生物。这种模式与N. maritimus通过两个古菌分子的头对头缩合和随后的所得无环四醚的环化来合成GDGT。这项研究提供了强大的信息GDGT在N的生物合成。进一步加深了我们对NH 4+供应对TEX 86代理的影响的理解。
Ammonia-oxidizing archaea (AOA) are among the most abundant microbes in the oceans and are one of the major sources of glycerol dibiphytanyl glycerol tetraethers (GDGTs) in the water column and underlying sediments. However, little is known about the mechanistic steps during biosynthesis of GDGTs that form the basis of the TEX86paleothermometer. Recent results showed that, apart from temperature, physiological factors such as growth stage and variations of the ammonium oxidation rate may affect the TEX86temperature proxy. We performed a short term incubation experiment with radiolabeled14C-bicarbonate to accurately trace the effect of high and low ammonium (NH4+) supply, on the production of individual membrane lipids by the AOA model organismNitrosopumilus maritimus. The14C incorporation during growth was monitored at five time intervals by liquid chromatography coupled to flow-through scintillation counting of the hydrolyzed membrane lipid extract, allowing a straight forward and sensitive on-line detection of14C incorporation into archaeal lipids on time-scales lower than a single cell cycle. The experiments showed that low NH4+supply results in higher cyclization of GDGTs with a preferential synthesis of crenarchaeol, whereas excess NH4+led to predominant production of GDGT-0. Consequently, the cultures with a high NH4+supply resulted in up to 10 °C lower estimated incubation temperatures than the cultures with low quantities of available NH4+using the TEX86Lcalibration. Interestingly, a high relative production of archaeol was observed at the beginning of all experiments (up to 27%), independent of the NH4+supply; likewise the degree of cyclization was initially lowest indicating delayed production of cycloalkylated derivatives. This pattern is consistent withN. maritimussynthesizing GDGTs by head-to-head condensation of two archaeol molecules and subsequent cyclization of the resulting acyclic tetraether. This study provides robust information on the biosynthesis of GDGTs inN. maritimusand advances our understanding of the influence of NH4+supply on the TEX86proxy.