Response of the freshwater alga Chlorella vulgaris to trichloroisocyanuric acid and ciprofloxacin

Abstract

The effects of trichloroisocyanuric acid (TCCA) and ciprofloxacin (CPFX) on the freshwater alga Chlorella vulgaris were assessed by toxicity bioassays and by the values of biomarkers in phase I and phase II. The biomarkers included growth rate, concentration of chlorophyll a, activities of 7-ethoxyresorufin-O-dealkylases (EROD), glutathione S-transferase (GST), catalase (CAT), and total glutathione (GSH). Ciprofloxacin was a weaker growth inhibitor than TCCA but, at a concentration of greater than 12.5 mg/L, decreased the growth of C. vulgaris. Concentration of chlorophyll a showed a similar trend. The 96-h median effective concentration (EC50; i.e., 50% reduction in growth relative to the control) of CPFX was 20.6 mg/L. Trichloroisocyanuric acid was a strong growth inhibitor and, at concentrations of greater than 0.80 mg/L, caused 100% inhibition on 24-h exposure. The 96-h EC50 of TCCA was 0.313 mg/L. Ciprofloxacin and TCCA affected the phase I and phase II enzyme activities differently. On exposure to CPFX, both EROD and GSH decreased at low CPFX concentrations (<5.0 mg/L) and increased at high CPFX concentrations (>12.5 mg/L), and CAT and GST exhibited induction at low concentrations and inhibition at high concentrations. In TCCA exposure, GST activity was significantly stimulated, and GSH concentration was increased. Catalase activity increased only at TCCA concentrations of greater than 0.12 mg/L, and no change in EROD activity was observed.

Ecotoxicological effects of ciprofloxacin on freshwater species: data integration and derivation of toxicity thresholds for risk assessment

“…The chronic toxicity of ciprofloxacin on P. subcapitata growth was similar to the one obtained by Halling-Sorensen et al (2000) (EC 50 = 2.97 mg L -1 ). Notwithstanding, the toxicity value obtained by Robinson et al (2005) for this species was almost one order of magnitude higher (EC 50 = 18.7 mg L -1 ), similarly to the one determined for Chlorella vulgaris (EC 50 -96 h = 20.6 mg L -1 ) by Ni et al (2008) (Table 2).…”

Toxicity of the fluoroquinolone antibiotics enrofloxacin and ciprofloxacin to photoautotrophic aquatic organisms

“…The presented PNECs for A. flos-aquae, D. subspicatus, and Lemna sp. are based on EC50 values published in previous studies [1,12,14,15,24] and on the EyC50 values obtained from the present study. Inhibition of yield was used as a representative endpoint that is comparable for all four species tested.…”

Ecotoxicological effects of enrofloxacin and its removal by monoculture of microalgal species and their consortium

“…The increased total chlorophyll content of C. pyrenoidosa and Microcystis aeruginosa was evident when exposed to spiramycin, and amoxicillin (Liu et al, 2014). A reduction in photosynthetic pigments is also a common stress response in plants and microalgae and can be caused by the peroxidation of thylakoid lipids and the degradation of PSII complexes (Nie et al, 2008). The total chlorophyll content of C. pyrenoidosa, Isochrysis galbana, and Tetraselmis chui significantly decreased due to the toxicity of chloramphenicol, florfenicol, and thiamphenicol (Lai et al, 2009).…”