Growth characteristics and growth modeling of Emp

Authors: Takashi Nagai Akio Imai Kazuo Matsushige Takehiko Fukushima

Publish Date: 2007/08/27

Volume: 8, Issue: 3, Pages: 261-270

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Abstract

Although iron is a key nutrient for algal growth just as are nitrogen and phosphorus in aquatic systems the effects of iron on algal growth are not well understood The growth characteristics of two species of cyanobacteria Microcystis aeruginosa and Planktothrix agardhii in ironlimited continuous cultures were investigated The relationships between dissolved iron concentration cell quota of iron and population growth rate were determined applying two equations Monod’s and Droop’s equations Both species produced hydroxamatetype siderophores but neither species produced catecholtype siderophores The cell quota of nitrogen for both M aeruginosa and P agardhii decreased with decreasing cell quota of iron The cell quota of phosphorus for M aeruginosa decreased with decreasing cell quota of iron whereas those for P agardhii did not decrease Iron uptake rate was measured in ironlimited batch cultures under different degrees of iron starvation The results of the iron uptake experiments suggest that iron uptake rates are independent of the cell quota of iron for M aeruginosa and highly dependent on the cell quota for P agardhii A kinetic model under iron limitation was developed based on the growth characteristics determined in our study and this model predicted accurately the algal population growth and iron consumption The model simulation suggested that M aeruginosa is a superior competitor under iron limitation The differences in growth characteristics between the species would be important determinants of the dominance of these algal species

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