MORPHOLOGICAL AND BIOCHEMICAL RESPONSES OF LEMNA MINOR L. (COMMON DUCKWEED) TO CIPROFLOXACIN

Active substances of pharmaceuticals occur not only in hospital waste or surface waters but also in rivers and seas in concentrations exceeding 1 mu g/l. As far as research is concerned, it is important to analyze the effect of pharmaceuticals on organisms other than their target organisms. It was the aim of this study to determine the phytotoxicity of increasing concentrations of soluble and insoluble ciprofloxacin (0; 0.0002; 0.0005; 0.0008; 0.001; 0.005; 0.01; 0.05; 0.1; 0.313; 0.63; 1.25; 2.5; 5; 10; 20; 40 mM) towards lesser duckweed. The phytotoxicity was evaluated on the basis of chosen morphological and biochemical features. In line with increasing concentrations, both soluble and insoluble ciprofloxacin present in the water caused reduction in yield, growth rate, amount of fresh mass, and chlorophyll content in duckweed tissues, with dry mass slightly growing. 1.25 mM of soluble ciprofloxacin was a lethal dose for the duckweed, since it hindered the growth rate and yield by 100%. Insoluble ciprofloxacin did not induce such a toxic effect even in its highest dose. The toxic effect of soluble ciprofloxacin also modified the content of soluble carbohydrates. For concentrations above 1.25 mM of soluble ciprofloxacin, the content of sucrose, D-chiro-inositol and monosaccharides dropped to zero. In 5 mM of soluble ciprofloxacin, acute dehydration of the tissues (the growth rate inhibited by more than 100%) led to a rapid increase in the content of myo-inositol. Yet, the content of soluble carbohydrates in the tissues of lesser duckweed was low and did not exceed 1% of fresh mass of the tissues.