The influence of nitrogen and growth phase on the toxicity of the cyanobacterial strain Microcystis PCC 7806
The worldwide occurrence of toxic cyanobacterial blooms and their numerous harmful effects have instigated extensive research into the environmental conditions promoting such events. Among the environmental factors which have been suggested to influence the increase in cyanobacterial proliferation,...
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Published in | Zbornik Matice Srpske za Prirodne Nauke Vol. 2019; no. 136; pp. 89 - 100 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Matica srpska
2019
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Subjects | |
Online Access | Get full text |
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Summary: | The worldwide occurrence of toxic cyanobacterial blooms and their numerous
harmful effects have instigated extensive research into the environmental
conditions promoting such events. Among the environmental factors which
have been suggested to influence the increase in cyanobacterial
proliferation, nutrient levels have been identified as one of the most
prominent, affecting the growth and toxic metabolite production of
cyano?bacteria in freshwater ecosystems. In the present study, toxicity of
the cyanobacterial strain Microcystis PCC 7806 was evaluated after growth in
media with three different nitrogen concentrations. The toxicity of
intracellular extracts was analyzed during different growth phases (after 7,
21, and 35 days of cultivation) by observing mortality rates in the Artemia
salina bioassay after 24h and 48h of exposure. The results have not shown
significantly higher mortality levels between the test organisms exposed to
extracts obtained from the cultures grown in the presence of higher nitrogen
content (1.5 g/l and 0.8 g/l) and those grown in a nitrogen-free medium. A
dose dependent effect, however, can be observed in most cases, with the most
substantial changes observed in the high-dose groups. Also, the toxic
effects and larval mortality increased during the exposure, suggesting the
time-dependent toxicity. Extracts obtained after longer periods of
cultivation (21 and 35 days) had stronger effects on the test organisms,
which indicates that the toxicity of the tested cyanobacterial strain
depends on the specific growth phase. |
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ISSN: | 0352-4906 2406-0828 |
DOI: | 10.2298/ZMSPN1936089D |