Alkaline phosphatase activity in the subtropical ocean: insights from nutrient, dust and trace metal addition experiments
Alkaline phosphatase activity in the subtropical ocean: insights from nutrient, dust and trace metal addition experiments
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DOI：
10.3389/fmars.2014.00073
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发表时间：
2014-01-01
影响因子：
3.7
通讯作者：
Lohan, Maeve C.
中科院分区：
文献类型：
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作者：
Mahaffey, Claire;Reynolds, Sarah;Lohan, Maeve C.
磷是地球上所有生命的必需营养素。在海洋中，最具生物利用性的磷是无机磷酸盐，但在广泛的亚热带环流中，磷酸盐浓度可能长期偏低，限制了初级生产力和固氮作用。在这些地区，生物产生水解酶，如碱性磷酸酶（AP），使他们能够利用更充分的溶解有机磷（DOP）池，以满足其细胞磷的需求。在这项研究中，我们综合了来自14项已发表研究的数据，并提出了我们自己的研究结果，从两个研究巡航（D326和D361）在东亚热带大西洋，探讨AP活动（阿帕）和营养物质，撒哈拉沙尘和微量金属之间的关系。我们发现，低于阈值磷酸盐浓度类似于30纳米，阿帕增加与磷酸盐浓度的反双曲线关系。同时，DOP浓度随着阿帕的增强而降低，表明DOP库的利用。我们发现，亚热带大西洋的阿帕率显著高于亚热带太平洋，即使在相同的低磷酸盐浓度范围内（0-50 nM）。虽然磷酸盐浓度可能有一个一阶控制阿帕率，我们推测，其他因素影响这个盆地规模的对比度。使用生物测定实验，我们表明，除了撒哈拉粉尘和锌显着增加阿帕的速率。据我们所知，我们的研究结果是第一个直接的实地证据表明，阿帕是有限的锌在亚热带海洋。需要进一步的工作，以探索微量金属，如铁和锌，这是磷酸水解酶，特别是PhoX和PhoA，分别辅因子，和阿帕在海洋之间的关系。
Phosphorus is an essential nutrient for all life on earth. In the ocean, the most bioavailable form of phosphorus is inorganic phosphate, but in the extensive subtropical gyres, phosphate concentrations can be chronically low and limit primary productivity and nitrogen fixation. In these regions, organisms produce hydrolytic enzymes, such as alkaline phosphatase (AP), that enable them to utilize the more replete dissolved organic phosphorus (DOP) pool to meet their cellular phosphorus demands. In this study, we synthesized data from 14 published studies and present our own findings from two research cruises (D326 and D361) in the eastern subtropical Atlantic to explore the relationship between AP activity (APA) and nutrients, Saharan dust and trace metals. We found that below a threshold phosphate concentration of similar to 30 nM, APA increased with an inverse hyperbolic relationship with phosphate concentration. Meanwhile, DOP concentrations decreased with enhanced APA, indicating utilization of the DOP pool. We found APA rates were significantly higher in the subtropical Atlantic compared to the subtropical Pacific Ocean, even over the same low phosphate concentration range (0-50 nM). While the phosphate concentration may have a first order control on the APA rates, we speculate that other factors influence this basin scale contrast. Using bioassay experiments, we show that the addition of Saharan dust and zinc significantly increased the rate of APA. To our knowledge, our results are the first direct field-based evidence that APA is limited by zinc in the subtropical ocean. Further work is required to explore the relationship between trace metals such as iron and zinc, which are co-factors of phosphohydrolytic enzymes, specifically PhoX and PhoA, respectively, and APA in the ocean.