Growth and plasmid profile in cyanobacteria exposed to salt and metal stresses
1999
Loveria, M.V.
Cyanobacteria are excellent organisms to serve as models for investigation of a wide variety of environmental conditions including, salinity and heavy metal uptake. This study was done to look at the effect of increasing concentrations of NaCl and cadmium on the growth (cell density and chlorophyll a content) and plasmid DNA profile of six strains/isolates of cyanobacteria: Synechococcus aquatilis 01 (Sy 01), S. sp. (Sy 03), Anabaena variabilis ATCC 29413, Anabaena Btg 01, Anabaena Pal 04 and Anabaena Pal 05. After adaptation of each strain/isolate to different salt concentration, 60 millimolar NaCl was found optimum for growth. Of the six strains, Anabaena Btg 01 Ab Pal 04 and Ab Pal 05 revealed to possess a more potential for salt tolerance. On the other hand, low concentration (0.05 ppm) of cadmium had no significant effect on growth of the strains studied. At higher concentration, growth was totally inhibited. Plasmid DNAs were found to be common among the six strains/isolates of cyanobacteria in NaCl-treated cells. Notable effects were observed after treatment with 180 mM and 240 mM NaCl. Two bands were observed to co-migrate with the marker in Sy01 and Sy03. However, plasmids were found to be absent in cells of A. variabilis ATCC 29413 and Anabaena Btgs 01 exposed to higher concentration of CdCl2. Results confirm the earlier studies that salt and heavy metal uptake in cyabacteria have significant effect on their growth characteristics and genotypes
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