Ammonium uptake by Chondrus crispus Stackhouse (Gigartinales,Rhodophyta) in culture |
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Authors: | Amat M. A. Braud J. -P. |
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Affiliation: | (1) Sanofi Bio-Industries, Usine de Baupte, 50500 Carentan, France |
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Abstract: | Cultivated Chondrus crispus was used in N-NH4 uptake experiments in the laboratory. An elevation of temperature increased the apparent rate of uptake, especially up to 11 °C. Uptake in the dark was found to be 83 % of that in the light. The apparent uptake decreased with increasing internal N pool; rates were 26.5, 22.2 and 20.2 µg N g dry wt–1 min–1 for internal N pools of 2.7, 3.5 and 4.6%, respectively. Apparent uptake increased with the substrate N concentration. The resulting curve has two components: an active uptake and a diffusion component at high (> 5000 µg N L–1) external N levels. Ks and Vmax were calculated by deducting the diffusion component from the uptake curve: these were of 497 µg N L –1 and 14.4 µg N g dry wt–1 min–1. respectively, and reflect a low substrate affinity. This could be the result of 10 years of continuous culture of C. crispus. Uptake was similarly followed in the culture tanks and showed comparable results; nighttime would be the most appropriate time to supply nutrients. |
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Keywords: | Chondrus crispus culture N-NH4 uptake Rhodophyta seaweed |
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