EFFECT OF ALGINATE IMMOBILIZATION OF NOSTOC COMMUNE ON THE KINETICS OF COPPER ION REMOVAL FROM AQUEOUS SOLUTIONS
DOI:
https://doi.org/10.31861/biosystems2026.02.289Keywords:
Nostoc commune, copper, immobilization, alginate gel, bioremediation, biosorption, bioaccumulation, heavy metalsAbstract
Increasing technogenic and military pressure on aquatic ecosystems in Ukraine, caused by combat operations, ammunition explosions, and the destruction of industrial infrastructure, creates an urgent need to develop and improve biotechnological approaches for water purification from heavy metals. Among military pollutants, copper occupies a specific position, as its high concentrations exert pronounced algicidal and cytotoxic effects on aquatic organisms. This study presents a comparative evaluation of copper ion removal efficiency from aqueous media using free-suspension and 1.5% alginate gel-immobilized cultures of the cyanobacterium Nostoc commune across a wide range of toxic loads (1–100 MAC) over a 15-day period. It was established that the immobilization of Nostoc cells within the alginate matrix restricts their proliferation rate (cell counts ranged within (1,8–2,2 ×106 cells/mL compared to 9,4–9,8 ×106 cells/mL in suspension), which is attributed to mechanical constraints and a diffusion barrier. However, the gel carrier maintains a consistently high cell viability level (77–92.4%) and effectively screens cyanobacteria from copper-induced stress during the initial cultivation phases. In contrast, the suspension culture under 100 MAC exhibited rapid cell mortality (viability dropped to 53% on day 3), followed by a population surge on days 12–15 due to a compensatory effect. Evaluation of copper removal dynamics via atomic absorption spectrometry confirmed the high decontamination capacity of both N. commune forms. Nevertheless, the immobilized system demonstrated a distinct advantage in the early stages, achieving maximum medium purification (residual copper content of approximately 30%) under 5 MAC on day 15. Coupling reduced biomass accumulation with consistently high metal-binding efficiency proves that immobilized N. commune cells possess a significantly higher specific sorption capacity per unit of biomass. High bioremediation efficiency is sustained by the synergy of initial ion-exchange sorption onto the alginate matrix and subsequent intracellular bioaccumulation. These findings confirm the strong potential of alginate-based N. commune formulations for deep water purification without generating substantial volumes of spent excess biomass.
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