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Limits to Microalgal Growth

  • M. Levasseur
  • P. A. Thompson
  • P. J. Harrison
Part of the Environmental Science Research book series (ESRH, volume 43)

Abstract

Our objectives were to determine: 1) the influence of different N forms (NH4 +, NO3, and urea) on the growth rate and on the nitrogen and carbon content of four microalgae, and 2) to relate the N form-induced physiological and biochemical differences to a shortage in energy (presumably reductant for NO3 reduction), or a rate-limiting step in the N uptake and/or assimilation. The use of NO3 instead of NH4 + resulted in a decrease in growth rate in Thalassiosira pseudonana and in significantly smaller N quotas and higher C:N ratios in T. pseudonana and Chaetoceros gracilis. Growth on urea instead of NH4 + resulted in a lower growth rate in C. gracilis and Gymnodinium sanguineum and in a lower N quota and a higher C:N ratio in most species tested. Growth on NO3 rather than on NH4 + often resulted in a smaller (less chlorophyll a cell−1) and less efficient (lower quantum yield for oxygen production, higher chlorophyll a fluorescence yield) photosynthetic system, suggesting that NO3 -grown cells were not energy-limited. On the other hand, since urea-grown cells have a reductant requirement similar to that of NH4 +-grown cells, the urea-induced decrease in growth rate and/or N quotas cannot be attributed to reductant limitation. The rate-limiting step for growth is more likely the activity of nitrate reductase (NR), nitrite reductase (NiR), or urease. Our results also show that symptoms of N limitation in algae (low N quotas, high C:N ratios) may be introduced by the N form, even at saturating N concentrations.

Keywords

Nitrate Reductase Nitrite Reductase Photosynthetic System Grown Cell MICROALGAL Growth 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Copyright information

© Springer Science+Business Media New York 1992

Authors and Affiliations

  • M. Levasseur
    • 1
  • P. A. Thompson
    • 2
  • P. J. Harrison
    • 2
  1. 1.Institut Maurice LamontagneMinistere des Peches et des OceansMont-JoliCanada
  2. 2.Department of OceanographyUniversity of British ColumbiaVancouverCanada

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