Toxicity and accumulation of selenite in four microalgae

Abstract

The toxicity and bioaccumulation of selenite in four microalgae,Spirulina platensis, Dunaliella salina, Dunaliella bardawill andPhaeodactylum tricornutum cultured in the presence of selenite were investigated. Lower concentrations of selenite were generally nontoxic and frequently stimulated algal growth, while higher concentrations of selenite inhibited algal growth. Selenite was more toxic toD. salina andD. bardawill than toS. platensis andP. Tricornutum. All algae cultured in selenite were able to incorporate Se to different degrees, which depended on algal species. The distributions of selenite among intracellular macromolecular compounds were different among algal species: most of the selenite was associated with proteins inS. platensis, D. salina andD. bardawill, while most of the selenite was associated with lipids inP. tricornutum, which reflected the physiological differences among the algae. These observations suggest that algae are able to accumulate selenite and bind it with intracellular macromolecular compounds when exposed to high concentration of selenite. This may represent a form of storage or detoxification of selenite by the algae.