Morphometry and growth of three <Emphasis Type="Italic">Synechococcus</Emphasis>-like picoplanktic cyanobacteria at different culture conditions |
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Authors: | Jitka Jezberová Jaroslava Komárková |
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Institution: | (1) Biological Center, Hydrobiological Institute of the Czech Academy of Sciences, České Budějovice, 37005, Czech Republic;(2) Faculty of Biological Sciences, University of South Bohemia, České Budějovice, 37005, Czech Republic |
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Abstract: | Three phycocyanin-rich strains of Synechococcus-like picoplanktic cyanobacteria, isolated from the plankton of Czech oligotrophic to eutrophic freshwater reservoirs, were
investigated in crossed gradients of light and temperature and in combination with two different culture media (BG-11 and
WC). The strains exhibited similar growth and reproduction patterns and displayed overlapping ranges of cell size (1.5 × 0.8
μm) under standardized laboratory conditions (18 μmol m−2 s−1; 20°C). However, strains behavior differed in the crossed gradients. All strains preferred BG-11 medium, where also remarkable
size changes could be observed. Length, width, cell abundance and growth rate of two strains were positively correlated with
temperature and nutrients, whereas the impact of light intensity was insignificant. Maximum cell elongation (involution cells
up to 19 μm) occurred in two strains only in BG-11 medium at highest temperature (28°C) and highest irradiance (53 μmol m−2 s−1). Cell dimensions in WC medium were constant under most conditions given. The third strain was influenced by all three factors,
from which light and nutrients played pivotal role. The length of the lag-phase for all strains appeared to be temperature
dependent (negative correlation). Despite the fact that the cell volume in all strains increased more than five times under
the lowest light and low temperature (6 μmol m−2 s−1, <15°C) in both media, the length/width ratio remained unchanged. The strains differed in the degree of cell enlargement
and cell division symmetry as well as in optimum temperature and light dependence. Based on this experimental work two strains
could be identified as Synechococcus sp. and one as Cyanobium sp., which can be used as a support for the following genetical analyses. |
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Keywords: | Cell elongation Crossed gradients Cyanobacteria Cyanobium Involution cells Light Morphometry Nutrients Synechococcus Temperature |
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