[Cellular response of freshwater green algae to the toxicity of tetracycline antibiotics].

Tetracycline antibiotics are a group of antibiotics which has been extensively used in most countries and are also the most widely used veterinary drugs and food additives in aquaculture and livestock industries of China. Because the substances are poorly adsorbed in the gut of animals and are only partially eliminated in sewage treatment plants, the antibiotics and their metabolites reach surface water where they may affect the aquatic organisms and human health. Herein, using green algae as test organisms, we studied the effects of tetracycline (TC), chlortetracycline (CTC) and deoxyteracycline (DC) on the cell permeability and growth inhibition of Chlorella pyrenoidosa and Scenedesmus obliquus. After 96 h of antibiotics exposure, the permeability of the cell membranes of both algae was decreased in the entire concentration range of doxycycline and was increased after exposure to a low concentration of tetracycline and chlortetracycline, then was decreased with the increase of the two antibiotics concentrations. The growth inhibiting effects of these three antibiotics on Chlorella pyrenoidosa and Scenedesmus obliquus were in an order of DC > TC > CTC. The ecotoxic response of Scenedesmus obliquus to tetracycline antibiotics was more sensitive than Chlorella pyrenoidosa.