Abstract
The current study included the isolation, purification and cultivation of blue-green alga Oscillatoria pseudogeminata G.Schmidle from soil using the BG-11liquid culture medium for 60 days of cultivation. The growth constant (k) and generation time (G) were measured which (K=0.144) and (G=2.09 days).
 Microcystins were purified and determined qualitatively and quantitatively from this alga by using the technique of enzyme linked immunosorbent assay (Elisa Kits). The alga showed the ability to produce microcystins in concentration reached 1.47 µg/L for each 50 mg DW. Tomato plants (Lycopersicon esculentum) aged two months were irrigated with three concentrations of purified microcystins 0.5 , 3.0 and 6.0 µg/L for 24 days. The results showed that the highest bioaccumulation of these toxins was found in the plant group treated with concentration 6.0 μg/L, with an average of 12.278 µg/L in the entire plant body, with a daily accumulation rate of 0.511 µg/day compared with control group and other treatments (p≤0.05).
 The highly accumulation of toxin was found in roots followed in descending order by stems and leaves respectively and were directly proportional to the increased concentration of purified microcystins. The study indicated that there were significant changes (p≤0.05) in the plant height, length of roots and surface area of the leaves and the leaves appeared pale green in color, which increased with increasing the concentration of purified toxin. The obtained results also showed a significant decrease in the concentration of carbohydrates and chlorophylls by increasing concentrations of purified toxins.
Highlights
Cyanobacteria found in different habitats including fresh, brackish, marine water and soil [1]
The safe levels of microcystins are approximately 0.3 μg/L in drinking water for children, while for other ages reach to 1.6 μg/L [6], but the concentration of these toxins may reach to 100 μg/L in some water bodies [7]
The algal cells contain visible gas vacuoles, which are regularly spread in the cytoplasm of the cell, which appear as black dots on the boundary between the cells forming the dermal thread and the thread ends with an around shape
Summary
Cyanobacteria (blue-green algae) found in different habitats including fresh, brackish, marine water and soil [1]. Several genera belonging to cyanobacteria as Microcystis, Anabaena, Oscillatoria, Haapalosiphon, Radiocystis, Stigonema, Lyngbya, Pseudoanabaena and Phormidium are known to produce microcystins (Hepatotoxins) and neurotoxins or both. Many species of blue green algae reach approximately to 80 species can produce hepatotoxin (Microcystins only) [5]. The safe levels of microcystins are approximately 0.3 μg/L in drinking water for children, while for other ages reach to 1.6 μg/L [6], but the concentration of these toxins may reach to 100 μg/L in some water bodies [7]. The proliferation of toxic and non-toxic bluegreen algae in aquatic habitats is well known as a famous phenomenon. The expansions of toxic species to a wide range may cause harmful effects on ecosystems [8]
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