Lubsch Alexander, Timmermans Klaas
NIOZ Royal Netherlands Institute for Sea Research, Department of Estuarine and Delta Systems, Utrecht University, PO Box 140, 4401 NT, Yerseke, the Netherlands.
Department Ocean Ecosystems, University of Groningen, PO Box 72, 9700 AB, Groningen, the Netherlands.
J Phycol. 2018 Apr;54(2):215-223. doi: 10.1111/jpy.12612. Epub 2018 Jan 16.
Dissolved inorganic phosphorus (DIP) is an essential macronutrient for maintaining metabolism and growth in autotrophs. Little is known about DIP uptake kinetics and internal P-storage capacity in seaweeds, such as Ulva lactuca (Chlorophyta). Ulva lactuca is a promising candidate for biofiltration purposes and mass commercial cultivation. We exposed U. lactuca to a wide range of DIP concentrations (1-50 μmol · L ) and a nonlimiting concentration of dissolved inorganic nitrogen (DIN; 5,000 μmol · L ) under fully controlled laboratory conditions in a "pulse-and-chase" assay over 10 d. Uptake kinetics were standardized per surface area of U. lactuca fronds. Two phases of responses to DIP-pulses were measured: (i) a surge uptake (V ) of 0.67 ± 0.10 μmol · cm · d and (ii) a steady state uptake (V ) of 0.07 ± 0.03 μmol · cm · d . Mean internal storage capacity (ISC ) of 0.73 ± 0.13 μmol · cm was calculated for DIP. DIP uptake did not affect DIN uptake. Parameters of DIN uptake were also calculated: V = 12.54 ± 1.90 μmol · cm · d , V = 2.26 ± 0.86 μmol · cm · d , and ISC = 22.90 ± 6.99 μmol · cm . Combining ISC and V values of P and N, nutrient storage capacity of U. lactuca was estimated to be sufficient for ~10 d. Both P and N storage capacities were filled within 2 d when exposed to saturating nutrient concentrations, and uptake rates declined thereafter at 90% for DIP and at 80% for DIN. Our results contribute to understanding the ecological aspects of nutrient uptake kinetics in U. lactuca and quantitatively evaluating its potential for bioremediation and/or biomass production for food, feed, and energy.
溶解无机磷（DIP）是自养生物维持新陈代谢和生长所必需的大量营养素。对于诸如石莼（绿藻门）等海藻中DIP的吸收动力学和内部磷储存能力，人们了解甚少。石莼是生物过滤和大规模商业养殖的理想候选对象。在完全受控的实验室条件下，我们通过“脉冲追踪”试验，让石莼在10天内暴露于一系列DIP浓度（1 - 50 μmol·L）和非限制性溶解无机氮（DIN；5000 μmol·L）浓度下。吸收动力学按石莼叶状体的表面积进行标准化。测量了对DIP脉冲的两个反应阶段：（i）激增吸收（V）为0.67±0.10 μmol·cm·d，（ii）稳态吸收（V）为0.07±0.03 μmol·cm·d。计算得出DIP的平均内部储存能力（ISC）为0.73±0.13 μmol·cm。DIP的吸收不影响DIN的吸收。还计算了DIN吸收的参数：V = 12.54±1.90 μmol·cm·d，V = 2.26±0.86 μmol·cm·d，ISC = 22.90±6.99 μmol·cm。结合P和N的ISC和V值，估计石莼的养分储存能力足以维持约10天。当暴露于饱和养分浓度时，P和N的储存能力在2天内就会填满，此后吸收速率下降，DIP下降90%，DIN下降80%。我们的研究结果有助于理解石莼养分吸收动力学的生态方面，并定量评估其在生物修复和/或用于食品、饲料和能源的生物质生产方面的潜力。
