Growth‐inhibiting effects of 12 antibacterial agents and their mixtures on the freshwater microalga Pseudokirchneriella subcapitata

Abstract

The growth-inhibiting and binary joint effects of 12 antibacterial agents on the freshwater green alga Pseudokirchneriella subcapitata (Korschikov) Hindák were investigated over 72-h exposures. The toxicity values (the median inhibitory concentration value, in micromoles) in decreasing order of sensitivity were triclosan (0.0018)>triclocarban (0.054)>roxithromycin (0.056)>clarithromycin (0.062)>tylosin (0.20)>tetracycline (2.25)>chlortetracycline (3.49)>norfloxacin (5.64)>sulfamethoxazole (7.50)>ciprofloxacin (20.22)>sulfamethazine (31.26)>trimethoprim (137.78). Several of these antibacterial compounds would be toxic at the micrograms per liter concentrations reported in surface waters and sewage effluents. Simple additive effects were observed in binary mixtures of sulfonamides, and most tylosin, triclosan, or triclocarban combinations. Potentially synergistic effects were observed in binary mixtures of the same class, such as macrolides, tetracyclines, and fluoroquinolones, as well as in some combined drugs, such as trimethoprim and sulfonamides or tylosin and tetracyclines. Potentially antagonistic effects were only observed between tylosin and triclocarban, triclosan and norfloxacin, and triclocarban and norfloxacin. Although present at low concentrations in the aquatic environment, mixtures of these antibacterial agents can potentially affect algal growth in freshwater systems due to their combined action.

Oxidation of triclosan by ferrate: Reaction kinetics, products identification and toxicity evaluation

“…Since algae were found to be very sensitive to triclosan [16,32,33], a freshwater unicellular green alga P. subcapitata was used to test toxicity changes during the oxidation of the compound by Fe(VI). The oxidation experiments were conducted at pH 7.0 at room temperature (23 ± 2 • C).…”

“…Growth inhibition tests of triclosan and its products to P. subcapitata over 72 h followed the procedure described by Yang et al [33]. The EC 50 value of triclosan was calculated by plotting the log concentration of triclosan versus algal cell counts using logistic regression (Eq.…”

Basin-scale emission and multimedia fate of triclosan in whole China

“…TCS has been detected in various environmental media such as influents, effluents and biosolids in WWTPs , rivers (Halden and Paull 2005;Lindstrom et al 2002;Sabaliunas et al 2003;Zhao et al 2013), lakes , drinking water (Stackelberg et al 2004) and ocean water (Xie et al 2008). Contamination of aquatic environments with TCS may be harmful to aquatic organisms, such as algae (Yang et al 2008), crustacean (Orvos et al 2002) and fish (Heidler et al 2006).…”

Triclosan as a surrogate for household biocides: An investigation into biocides in aquatic environments of a highly urbanized region

“…Moreover, those biocides present in the aquatic environment can cause adverse effects on aquatic organisms. For example, triclosan has shown toxicity to algae species with a reported 72 h-growth no-observed-effect concentration (NOEC) of 200 ng/L (Yang et al, 2008). Parabens are confirmed to be weak estrogenic compounds (Routledge et al, 1998), and azole fungicides are regarded as potential endocrine disruptors due to their aromatase inhibition (Zarn et al, 2003).…”