Morpho-physiological responses by Isochrysis galbana Parke to different concentrations of oxytetracycline.

The pollution of aquatic bodies by pharmaceutical compounds is an emerging environmental problem, with little explored consequences. Oxytetracycline (OTC) is an antibiotic used for treatment of infections caused by a variety of microorganisms and it is widely employed in medicine, livestock husbandry and aquaculture. This pharmaceutical compound may cause deleterious effects on non-target aquatic organisms as microalgae. The objective of this study was to evaluate the effects of OTC on growth, pigment content and morpho-physiology of the microalga Isochrysis galbana Parke. The results highlighted that OTC exposure inhibited the growth of I. galbana in cultures treated with OTC 5.0 and 10.0 mg/L after 3 days and in cultures treated with OTC 5.0, 7.5 and 10.0 mg/L after 5 days. Effects of OTC on cells ultrastructure and physiology consisted in large cytoplasmic lipid inclusions and in a decrease of photosynthetic pigments amount.