Subcellular distribution of fluoranthene in Chlorella vulgaris with the presence of cetyltrimethylammonium chloride

This study explored the possible mechanism of the joint toxicity of binary mixtures of cetyltrimethylammonium chloride (CTAC) and fluoranthene (Flu) to the green alga Chlorella vulgaris by examining the subcellular distribution of Flu within the alga. The joint action of CTAC (100 μg L−1) and Flu (0-200 μg L−1) on the algae changed from a synergetic effect (0-50 μg L−1) to an antagonistic effect (50-200 μg L−1) with an increase of the Flu concentration. The Flu uptake was enhanced by the presence of CTAC through the intracellular detection of Flu. Furthermore, the highest amount of Flu bound to the cytosol, whereas the least amount bound to the cellular debris when synergistic effect was observed at 2.5 μg L−1 Flu. However, the highest amount of Flu bound to the cellular debris, whereas the least amount bound to the organelles when antagonistic effect was displayed at 200 μg L−1 Flu. The different subcellular distribution of Flu may affect the uptake of the highly toxic CTAC by the algae in the binary mixture, and consequently lead to a different level of CTAC toxicity. The abovementioned results indicate that the subcellular distribution of chemicals can be used to elucidate possible mechanisms for the joint toxicity of their binary mixtures to aquatic organisms.

► The joint action of CTAC and Flu on Chlorella vulgaris changed from synergism to antagonism. ► The uptake of Flu by algae was enhanced with the presence of CTAC. ► The highest amount of Flu bound to the cytosol when synergism was observed. ► The highest amount of Flu bound to the cellular debris when antagonism was displayed. ► Subcellular distribution could elucidate the possible mechanism of joint toxicity.