EVALUATION OF COMPETITIVE ABILITY OF <i>STAURASTRUM LUETKEMUELLERII</i> (CHLOROPHYCEAE) AND <i>MICROCYSTIS AERUGINOSA</i> (CYANOPHYCEAE) UNDER P LIMITATION¹

• Yngvar Olsen

抄録

The desmid Staurastrum luetkemuellerii Donat et Ruttner and the cyanobacterium Microcystis aeruginosa Kütz. showed pronounced differences in chemical composition and ability to maintain P fluxes. The cellular P:C ratio (Q p ) and the surplus P:C ratio (Q sp ) were higher in M. aeruginosa , indicating a lower yield of biomass C per unit of P. The subsistence quota (Q p ) was 1.85 μg P·mg C −1 in S. luetkemuellerii and 6.09 μg P·mg C −1 in M. aeruginosa , whereas the respective Q p of P saturnted organisms (Q s ) were 43 and 63 μg P·mg C −1 . These stores could support four divisions in S. luetkemuellerii and three divisions in M. aeruginosa , which suggests that the former exhibited highest storage capacity (Q s /Q 0 ). M. aeruginosa showed a tenfold higher activity of alkaline phosphatase than S. luetkemuellerii when P starved. The optimum N:P ratio (by weight) was 5 in S. luetkemuellerii and 7 in M. aeruginosa. The initial uptake of P i pulses in the organisms was not inhibited by rapid (<1 h) internal feedback mechanisms and the short term uptake rote could be expressed solely as a function of ambient P i . The maximum cellular C‐based uptake rate (V m ) in P starved M. aeruginosa was up to 50 times higher than that of S. luetkemuellerii . It decreased with increasing growth rate (P status) in the former species and remained fairly constant in the latter. The corresponding cellular P‐based value (U m = V m /Q p ) decreased with growth rate in both species and was about 10 times higher in P started M. aeruginosa than in S. luetkemuellerii . The average half saturation constant for uptake (K m ) was equal for both species (22 μg P·L −1 ) and varied with the P status. S. luetkemuellerii exhibited shifts in the uptake rate of P i that were characterized by increased affinity (U m /K m ) at low P i , concentrations (<4 μg P·L −1 ) compared to that at higher concentrations. The species thus was well adapted to uptake at low ambient P i , but M. aeruginosa was superior in P i uptake under steady state and transient conditions when the growth rate was lower than 0.75 d −1 . Moreover, M. aeruginosa was favored by pulsed addition of P i . M. aeruginosa relpased P i at a higher rate than S. luetkemuellerii . Leakage of P i from the cells caused C‐shaped μ vs. P i curves. Therefore, no unique K s for growth could be estimated. The maximum growth rate (μ m ) (23° C) was 0.94 d −1 for S. luetkemuellerii and 0.81 d −1 for M. aeruginosa . The steady state concentration of P i (P*) was lower in M. aeruginosa than in S. luetkemuellerii at medium growth rates. The concentration of P i at which the uptake and release of P i was equal (P c was, however, lower in S. luetkemuellerii .

収録刊行物

• Journal of Phycology

  Journal of Phycology 25 (3), 486-499, 1989-09

  Wiley

キーワード

• Plant Science
• Aquatic Science

詳細情報

• CRID: 1360574095484102784
• NII論文ID: 30014853325
• DOI: 10.1111/j.1529-8817.1989.tb00254.x
• ISSN: 15298817
• ISSN: 00223646
• Web Site: https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1529-8817.1989.tb00254.x
• Web Site: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1529-8817.1989.tb00254.x
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