ABSTRACT
IR spectra of metal treated live Spirulina sp. and dead Spirulina sp. are not exactly the same. The important difference is observed at 1650 cm-1 on uptake of metal ions by live Spirulina sp. This band changes (red shift) appreciably in metal treated live species, which was not the case for dead Spirulina sp., indicating significant interaction of metal ions with the amide/amino group in the former. Membrane bound transport enzymes in live Spirulina sp. help in intracellular interaction of metal ions with amino acid. The carboxylate moiety of fatty acids also takes part in the sorption process. The interaction with carboxylate is stronger in Ni+2 and Cr2O7
–2 treated biomass, while in case of Cu+2 and Cr+3, the position of the peaks due to carboxylate change but intensity does not change appreciably (Doshi et al. 2007a). As in dead, in live Spirulina sp. too metal ions interact with hydroxyl and phosphate moiety. This interaction is very pronounced with Cr2O7
–2 and Cu+2 ions. In case of metal uptake by dead Spirulina sp., primarily phosphate,
hydroxyl and carboxylate groups take the lead role. The high metal uptake by live Spirulina sp. may be traced to the metal transport through the cell in presence of active enzymes thereby all the functional groups of intercellular biopolymer matrix. Live algae possess intracellular polyphosphates which participate in metal sequestration, as well as algal extracellular polysaccharides that serve to chelate or bind metal ions (Zhang and Majidi 1994, Tropis et al. 1996).
