Assessment of the metal removal capability of two capsulated cyanobacteria, Cyanospira capsulata and Nostoc PCC7936 |
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Authors: | Roberto De Philippis Raffaella Paperi Claudio Sili Massimo Vincenzini |
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Affiliation: | (1) Dipartimento di Biotecnologie Agrarie, Universitá degli Studi, Piazzale delle Cascine 24, Firenze, I 50144, Italy;(2) Istituto per lo Studio degli Ecosistemi, CNR, Piazzale delle Cascine 24, Firenze, I 50144, Italy |
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Abstract: | Two capsulated, exopolysaccharide-producing cyanobacteria, Cyanospira capsulata and Nostoc PCC7936, were tested with regard to their metal removal capability by using copper as model metal. The experiments, carried out with the sole cyanobacterial biomass suspended in distilled water and confined into small dialysis tubings, showed that C. capsulata biomass is characterized by the best efficiency in metal removal, with a qmax (maximum amount of copper removed per biomass unit) of 96 ± 2 mg Cu(II) removed per g of protein in comparison with the value of 79 ± 3 of Nostoc PCC7936 biomass. The experimental data obtained with both cyanobacterial biomass best fit the Langmuir sorption isotherm. The sorption of copper started from the first minutes of contact with the metal and attained the equilibrium state, when no more copper removal was evident, after 5 and 6 hours, for C. capsulata and Nostoc PCC7936, respectively. The best efficiency in Cu(II) removal was obtained at pH 6.1–6.2, while the presence of Mg2+ or Ca2+ reduced copper removal capability of both species to 60–70% of their qmax. The results showed that the biomass of C. capsulata and Nostoc PCC7936 possesses a high affinity and a high specific uptake for copper, comparable with the best performances shown by other microbial biomass, and suggest the possibility to use the capsulated trichomes of the two cyanobacteria for the bioremoval of heavy metals from polluted water bodies. |
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Keywords: | Capsule Copper bioremoval Cyanospira capsulata Exopolysaccharide-producing cyanobacteria Exopolysaccharide Metal bioremoval Nostoc PCC7936 |
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