Abstract:
Among the commercialized microalgae, increasing attention is being focused on Spirulina plantensis, because of its multi-nutritional properties and other benefits. Taking in to consideration that the chemical composition of an organism could vary with environmental conditions, the present study was focused on the effect of Pb2+ on phycobiliprotein content of S. platensis. The test was conducted in Zarrouk liquid medium containing various Pb2+ concentrations (0, 1, 10, 30, 50 and 100 µg/mL). At the end of 10 d culture period, the cultures were subjected to analysis of principal phycobiliiproteins; phycocyanin (CPC), allo-phycocyanin (APC) and phycoerythrin (PE) contents. The growth of S. platensis was also monitored routinely by counting cells. Though, Pb2+ high concentrations could adversely affect growth (2.29, 37.95, 49.94 and 82.0% inhibitions respectively at 10, 30, 50 and 100 µg/mL), a slight growth stimulation was seen at low concentration (1 µg/mL). Phycobiliiprotein contents were also found to have decrease with the increased Pb2+ concentration in the medium. The highest reductions (68.4, 65.5 and 83.3% respectively for CPC, APC andPE) were observed at 100 µg/mL. Results further revealed that reductions in phycoerythrin contents at 50 and 100 µg/mL of Pb2+ were remarkably higher than those of the other two pigments. Metal induced changes in the arrangement and structure of the photosystem II, the multiprotein complex localized in the arrangement and structure of the photosystem II, the multiprotein complex localized in the thylakoid membrane could be the possible reason for decreased Phycobiliiprotein contents at a higher concentration of Pb2+.
