Bioaccumulation of Pb2+ and its effects on growth, morphology and pigment contents of Spirulina (Arthrospira) platensis.

Abstract

A laboratory experiment was conducted to assess the bioaccumulation of Pb2+ and its effects on growth, morphology and pigment contents of Spirulina (Arthrospira) platensis. The specimen cultured in Zarrouk liquid medium was treated with various initial metal concentrations (0, 5, 10, 30, 50 and 100 μgmL-1). The growth of S. platensis was adversely affected by Pb2+ at high con centrations (30, 50 and 100μgmL-1). However, at low concentrations (5μgmL-1), Pb2+ could stimulate its growth slightly. The pig ment contents (chlorophyll α and β carotene) were decreased in a dose-dependent manner. The highest reductions (67% and 53% respectively in chlorophyllα and β carotene) were observed in 100μgmL-1treatment group. The LC50 (96 h) of Pb2+ was measured as 75.34μgmL-1. Apart from a few cases of filament breakages at elevated concentrations (50 and 100μgmL-1), morphological abnor malities are not specific. Metal bioaccumulation increased with Pb2+ concentrations, but decreased with exposure time. The maxi mum accumulated amount was 188mg g-1 dry weight. The bioconcentration factor (BCF) reached to a peak at day 2, followed by a gradual reduction for all the exposure concentrations. S. platensis is able to tolerate considerably high Pb2+ concentrations. Conse quently it can be used as a potential species to remove heavy metal from contaminated waters.