Effect
of nitrogen and phosphorus on growth and microcystin production in
three Microcystis species
K.L.
Lee1, K.Y. Jung2, J.H. Kim4,? Y.S. Kim3
and H.S. Kim3*
1Watershed Ecology
Research Team, National Institute of Environmental Research,?? Incheon,
22689, South Korea
2Nakdong River
Environment Research Center, National? Institute of Environmental Research,
Gyeongsangbuk-do, 40103, South Korea
3Department of Biology,?
Kyungpook National University, Daegu, 41566, South Korea
4Microorganism
Resources Division, National Institute of Biological Resources, Incheon,
22689, South Korea
*Corresponding
Author E-mail: kimhsu@knu.ac.kr
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Key
words
Cyanobacterial blooms
Freshwater ecosystem
Microcystin
Microcystis
species
Nitrogen & Phosphorus
Publication Data
Paper received : 08.04.2017
Revised received : 13.07.2017
Re-revised received :
06.09.2017
Accepted : 29.09.2017
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Abstract
Aim: The effects of
nitrogen and phosphorus concentration on growth and microcystin
production were investigated in three species of bloom-forming Microcystis
isolated from two South Korean freshwater systems.
Methodology:
Three
species of cyanobacteria were collected from Yeongchun Dam and Ankei Dam in
Kyungpook Province, South Korea. Culture experiments were conducted at 25 ? 1?C
under cool white fluorescent light (ca. 50 μmol m-2 s-1)
in media with different concentrations of nitrogen (0 to 20 mg l-1)
and phosphorus (0 to 5 mg l-1). Cell numbers were determined in a
hemocytometer for calculation of growth rate. Microcystin was analysed using
high pressure liquid chromatography.
Results:
The
highest growth rate (μmax) and maximal microcystin production
occurred at nitrogen concentrations of 10 and 20 mg l-1 in all
three species. The response to phosphorus concentration was more complex. The
highest growth rate (μmax) of M. aeruginosa, M.
ichthyoblabe and M. viridis occurred at phosphorus concentrations
of 0.5 mg l-1, 0.1 mg l-1, and 3 mg l-1,
respectively. M.aeruginosa also had maximal microcystin
production at 0.5 mg l-1 P. In contrast, M.ichthyoblabe and
M. viridis had high microcystin production at 0 mg l-1 and at 5 mg
l-1 P (the highest tested concentration), and low microcystin
production at 0.1 mg l-1 P. Thus at 0.1 mg l-1, M.ichthyoblabe
had the highest growth rate but produced least amount of microcystin. The
types of microcystins produced varied according to species and nutrient
conditions.
Interpretation:
Microcystin
production and growth in Microcystis species isolated from South Korea
varied according to species and nutrient conditions. These species responded
similarly to different nitrogen concentrations, but differently to different
phosphorus concentrations.
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