Dissolved organic phosphorus molecular weight fractionation and apparent bioavailability quantified via coupled sequential ultrafiltration and enzyme hydrolysis
Dissolved organic phosphorus molecular weight fractionation and apparent bioavailability quantified via coupled sequential ultrafiltration and enzyme hydrolysis
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DOI：
10.1002/lom3.10498
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发表时间：
2022-07
期刊：
影响因子：
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通讯作者：
Danielle K. Hull;K. Ruttenberg
中科院分区：
文献类型：
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作者：
Danielle K. Hull;K. Ruttenberg
当磷酸盐水平不足以满足其P需求时，水生生物利用溶解有机磷（DOP）。它在支持初级生产中的关键作用促使人们努力表征DOP的组成并深入了解其生物利用度。31 P核磁共振（31 P-NMR）光谱是水生地球化学家目前用于确定大量海洋DOP池组成方面的主要工具，它提供了超出直接P键合环境的有限组成细节，并且没有提供DOP潜在生物利用度的定量信息。因此，DOP池的特征仍然很差，限制了相对于DOP生物利用度的预测能力。我们已经开发了一个连续的超滤（SUF）方法分离的DOP池成四个不同的分子量范围。然后将浓缩的分子量级分与磷酸水解酶一起孵育，以确定单酯和二酯结合的P的潜在生物利用度。使用已知分子量的市售DOP化合物作为天然存在的DOP的类似物，验证DOP分子量分离。我们已经应用了SUF方法，从近岸样带在Kāne'ohe湾，夏威夷，和表面沃茨贫营养站ALOHA（夏威夷海洋时间序列）的地表水样品。这些现场测试的结果表明，耦合SUF生物利用度方法揭示了海洋DOP池的组成复杂性比31 P-NMR研究所解决的更大。值得注意的是，SUF生物利用度方法不需要昂贵的、技术上复杂的仪器（例如，31 P-NMR），因此对于希望探测海洋DOP组合物的研究人员来说是容易获得的，这些研究人员不具有31 P-NMR的访问权或专业知识。
Aquatic organisms utilize dissolved organic phosphorus (DOP) when phosphate levels are insufficient to satisfy their P‐demand. Its critical role in supporting primary production has motivated efforts to characterize DOP composition and gain insight into its bioavailability. 31P nuclear magnetic resonance (31P‐NMR) spectroscopy, the principal tool currently used by aquatic geochemists to identify compositional aspects of the bulk marine DOP pool, has provided limited compositional detail beyond the immediate P‐bonding environment, and does not provide quantitative information on potential bioavailability of DOP. As a result, the DOP pool remains poorly characterized, limiting predictive power relative to DOP bioavailability. We have developed a sequential ultrafiltration (SUF) method to segregate the DOP pool into four distinct molecular weight ranges. The concentrated molecular weight fractions are then incubated with phosphohydrolytic enzymes to determine the potential bioavailability of monoester‐ and diester‐bound P. DOP molecular weight segregation was verified using commercially available DOP compounds of known molecular weight as analogues for naturally occurring DOP. We have applied the SUF method to surface water samples from a nearshore transect in Kāne'ohe Bay, Hawai'i, and surface waters from oligotrophic Station ALOHA (Hawai'i Ocean Time Series). Results of these field tests indicate that the coupled SUF‐bioavailability method reveals greater compositional complexity of the marine DOP pool than has been resolved by 31P‐NMR studies. Notably, the SUF‐bioavailability method does not require expensive, technically complicated instrumentation (e.g., 31P‐NMR), and thus is readily accessible to researchers wishing to probe marine DOP composition who do not have access to or expertise in 31P‐NMR.