Overestimation of prokaryotic production by leucine incorporation-and how to avoid it
Overestimation of prokaryotic production by leucine incorporation-and how to avoid it
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DOI：
10.1002/lno.12032
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发表时间：
2022-02-08
影响因子：
4.5
通讯作者：
Evans, Claire
中科院分区：
文献类型：
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作者：
Giering, Sarah L. C.;Evans, Claire
原核生物在水生生态系统中发挥着核心作用，消耗水生初级生产产生的约一半有机物质，其中一小部分用于生长。准确测量这种原核生物量生产是理解水生碳和营养循环的关键，因为它有助于驱动控制大气碳含量等参数的生物地球化学过程。水生原核生物量的生产通常是估计在放射性示踪剂实验中的氨基酸亮氨酸的掺入率-一种自20世纪80年代以来广泛使用的方法。在这里，我们评估的基本假设的方法，重点是相关的转换因子，并审查他们的经验数据的背景下。我们证明，常用的理论转换因子不能占亮氨酸的使用作为从头蛋白质合成和呼吸的前体。因此，当应用标准转换因子时，原核生物量生产可能被大大高估。受影响最严重的是公海、中层和底栖环境，其中25%的估计数可能分别被高估至少6.1、4.9和6.5倍。我们提出了一个改进的碳-亮氨酸转换因子，并提出了改进和选择合适的实验方案的建议。
Prokaryotes play a central role in aquatic ecosystems by consuming approximately half of the organic matter produced by aquatic primary production, of which a fraction is used for growth. Accurately measuring this prokaryotic biomass production is key to understanding aquatic carbon and nutrient cycles, since it is instrumental in driving biogeochemical processes that control parameters such as atmospheric carbon content. Aquatic prokaryotic biomass production is typically estimated from incorporation rates of the amino acid leucine during radiotracer experiments-a method widely used since the 1980s. Here we evaluate the underlying assumptions of the method with a focus on the associated conversion factors and review them in the context of empirical data. We demonstrate that the commonly used theoretical conversion factors fail to account for leucine's use as precursor for de novo protein synthesis and its respiration. As a consequence, prokaryotic biomass production is likely considerably overestimated when applying the standard conversion factors. Most severely affected are open-ocean, mesopelagic and benthic environments, where 25% of the estimates are likely to be overestimated by at least a factor of 6.1, 4.9, and 6.5, respectively. We propose a refined carbon-to-leucine conversion factor and make recommendations for improving and selecting appropriate experimental protocols.