The toxicity and bioaccumulation of selenate, selenite and seleno-L-methionine in the cyanobacterium Anabaena flos-aquae.

A laboratory investigation was conducted to study the toxicity and bioaccumulation of seleno-L-methionine, selenate and selenite in the cyanobacterium Anabaena flos-aquae. The first sub-lethal effects of seleno-L-methionine, selenite and selenate occurred at 0.1, 3.0, and 3.0 mg/L, respectively with a decrease in chlorophyll a concentration (P less than 0.0001). Selenium bioconcentration factors (BCF) were in the order of seleno-L-methionine, selenite, and selenate. Significant decreases in intracellular selenium concentration were observed at both the no effect (NOEL) and low effect levels (LOEL) at each oxidation state tested in the given experiment (p less than 0.0001). Mechanisms for the assimilation, toxicity and regulation of selenium are presented.