Absorción De Metales Pesados

Biosorption of heavy metals influenced by the chemical composition of Spirulina sp. (Arthrospira) biomass.

Hernandez E, Olguin EJ.

Environmental Biotechnology Department, Institute of Ecology, AP. 63., Xalapa, Mexico.

The capacity of Spirulina sp. cells with different chemical composition for Pb (II), Cd (II) and Cr (VI) sorption, was evaluated. Four different types of Spirulina biomass with a different chemical composition were tested. Two of them contained a high percentage of protein (68.95 +/- 0.30 and 63.73 +/- 0.25%) as a result of being cultivated in Zarrouk medium and exposedat two light intensities (66 micromol photon m(-2) s(-1) and 144 micromol photon m(-2) s(-1)) in batch cultures. A third type of biomass, cultivated in a “Complex” medium and exposed at 66 micromol photon (m-2) s(-1), contained a high percentage of lipids (30.08 +/- 1.92. Finally, the fourth type of biomass was enriched in polysaccharides (25.54 +/- 0.51%) as a result of being cultivated in the “Complex” medium, but exposed at 144 micromol photon m(-2) s(-1). It was found that the chemical composition of Spirulina sp. cells did have a strong influence on their adsorption capacity. The maximum adsorption capacities (q(max)) for Pb and Cd were highest (172.41 and 54.05 mg g(-1) of cells, at pH 5.0 and 4.5 respectively) when cells exhibited the higher polysaccharide content. In the case of Cr VI, the highest q(max), was exhibited by cells cultivated in Zarrouk medium and showing the higher protein content (at pH 2.0). pH did not affect the adsorption of Pb II in the range of 3 to 5.5, nor of Cd in the range of 4 to 7. For Cr VI, adsorption was observed only at a pH equal to 2 or lower.

PUB: Environ Technol. 2002 Dec;23(12):1369-77.

Modulatory potential of Spirulina fusiformis on testicular phosphatases in Swiss albino mice against mercury intoxication.

Saxena PS, Kumar M.

Department of Zoology, University of Rajasthan, India.

Administration of mercuric chloride (HgCl2; 5.0 mg/kg body weight) to male Swiss albino-mice resulted in significantly higher levels of testicular acid phosphatase (ACP) and alkaline phosphatase (ALP) activities as compared to control. In combination group where S. fusiformis (800 mg/kg body weight) was given before and after HgCl2 treatment, the mercury induced toxicity reduced in terms of decreased levels of ACP and ALP activities in the testis. The animal treated with only Spirulina did not show any alteration in ACP and ALP values. It is suggested that oral administration of Spirulina can modulate mercury induced testicular toxicity.

PUB: Indian J Exp Biol. 2004 Oct;42(10):998-1002.

Bioremediation potential of spirulina: toxicity and biosorption studies of lead.

Chen H, Pan SS.

Department of Environmental Engineering, Zhejiang University, Hangzhou, China.

This study examines the possibility of using live spirulina to biologically remove aqueous lead of low concentration (below 50 mg/L) from wastewater. The spirulina cells were first immersed for seven days in five wastewater samples containing lead of different concentrations, and the growth rate was determined by light at wavelength of 560 nm. The 72 h-EC50 (72 h medium effective concentration) was estimated to be 11.46 mg/L (lead). Afterwards, the lead adsorption by live spirulina cells was conducted. It was observed that at the initial stage (0-12 min) the adsorption rate was so rapid that 74% of the metal was biologically adsorbed. The maximum biosorption capacity of live spirulina was estimated to be 0.62 mg lead per 10(5) alga cells.

PUB: J Zhejiang Univ Sci B. 2005 Mar;6(3):171-4.

Phytoremediation potential of Spirulina (Arthrospira) platensis: biosorption and toxicity studies of cadmium.

Rangsayator N, Upatham ES, Kruatrachue M, Pokethitiyook P, Lanza GR.

Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.

This study examines the possibility of using Spirulina (Arthrospira) platensis TISTR 8217 to remove low concentrations of cadmium (less than 100 mg/l) from wastewater. The cyanobacteria were exposed to six different cadmium concentrations for 96 h, and the growth rate was determined using an optical density at 560 nm. The inhibiting concentration (IC50) was estimated using probit analysis. The IC50 at 24, 48, 72, and 96 h were 13.15, 16.68, 17.28, and 18.35 mg/l Cd, respectively. Cellular damage was studied under a light microscope and a transmission electron microscope. Swollen cells and fragmented filaments were observed. Cell injury increased with increasing concentrations of cadmium. Ultrastructural changes were observed in the algae exposed to cadmium concentrations both close to IC50 (14.68 mg/l) and at IC50 (18.35 mg/l). The alterations induced by cadmium were disintegration and disorganization of thylakoid membranes, presence of large intrathylakoidal space, increase of polyphosphate bodies, and cell lysis. In addition, the cadmium adsorption by algal cells was studied. Environmental factors were found to have an effect on biosorption. The uptake of cadmium was not affected by the temperature of the solution, but the sorption was pH dependent. The optimum pH for biosorption of algal cells was 7. The cadmium uptake process was rapid, with 78% of metal sorption completed within 5 min. The sorption data fit well to the Langmuir isotherm. The maximum adsorption capacity for S. platensis was 98.04 mg Cd per g biomass.

PUB: Environ Pollut. 2002;119(1):45-53.