EC Pharmacology and Toxicology

The study examined the effect of various nitrogen sources on heterocyst frequency in Nostoc punctiforme using BG-11 medium. Various concentrations of sodium nitrate, calcium nitrate, potassium nitrate, ammonium nitrate, and urea were tested. The results indicated that nitrogen-deficient conditions promoted higher heterocyst frequency (10.16%), compared to nitrogen-supplemented environments, while ammonium nitrate and urea exhibited inhibitory effects (0%). Other sources, such as sodium, calcium, and potassium nitrates, have varying effects, with sodium nitrate (1.5 g/L in BG-11 medium) yielding a frequency of 5.74%. Morphological analyses revealed adaptations in filament structure related to nitrogen availability. The nitrogen supplementation resulted in longer, less twisted filaments and a reduced presence of heterocysts. Findings emphasize the regulatory role of nitrogen sources in heterocyst formation, providing insights into the ecological adaptability of cyanobacteria to nitrogen availability, with implications for agricultural practices, biofertilization and environmental management.

 Keywords: Ammonium Nitrate; Cyanobacteria; Heterocyst Frequency; Nitrogen Sources; Nostoc punctiforme

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