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  • Omega Lasienhun Diengdoh North-Eastern Hill University
  • Sukjailin Ryntathiang North-Eastern Hill University
  • Mayashree B Syiem North Eastern Hill University


Anabaena variabilis MEGCH1, Zinc toxicity, Carbon and nitrogen fixation and assimilation, SEM, TEM study


The present work was conducted to check the effects of Zn exposure (10 - 100 µM) in the cyanobacterium Anabaena variabilis MEGCH1 over a period of seven days. The Zn concentration, even the lowest limit considered for the study, was substantially higher than that is generally found in coal mine contaminated wastewater. Most biochemical parameters in the organism showed marked tolerance towards Zn exposure up to a concentration of ~ 30 µM, although, in the presence of a higher Zn concentration, the organism showed substantial changes in its biomass, morphology, and ultrastructure, indicating the toxic nature of chronic Zn exposure. Similar toxicity was also evident in the entire C-fixation machinery, including the photosynthetic pigments, rate of photosynthetic and respiratory electron transport chain activities, and total carbohydrate content. There were negative impacts recorded on the heterocysts’ frequency as well as on nitrogenase and glutamine synthetase enzyme activities that resulted in poor nitrogen fixation and assimilation. Consequently, the level of soluble protein content within the cells was also reduced. These adverse effects were reflected in an obvious decrease in total biomass production. The increase in the total proline content of the treated culture clearly indicated that the organism was under obvious stress under Zn exposure. The cyanobacterium's survival and performance, however, in the presence of significant Zn ions in its surroundings, indicated that the organism could be considered for bioremediation technologies.


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How to Cite

Diengdoh, O. L., Ryntathiang, S., & Syiem, M. B. (2023). ZN TOLERANCE IN ANABAENA VARIABILIS MEGCH1: AN IN-DEPTH ANALYSIS OF CARBON AND NITROGEN ASSIMILATION; MORPHOLOGY AND ULTRASTRUCTURE. Journal of Applied Biological Sciences, 17(3), 391–406. Retrieved from https://jabsonline.org/index.php/jabs/article/view/1138