Aquatic toxicity of antibiotic contaminant doxycycline hydrochloride on cyanobacterium microcystis aeruginosa

Veterinary antibiotics have been used extensively in many countries to treat diseases and protect the health of animals. As they are poorly adsorbed in the gut of the animals, the majority of antibiotics are excreted unchanged in faeces and urine. Therefore, antibiotic contaminants in aquatic ecosystems may pose physiological effects on aquatic lives. In the present study, growth inhibition and oxidative damage in cyanobacteria Microcystis aeruginosa exposed to doxycycline hydrochloride were investigated. The results showed that doxycycline hydrochloride could inhibit the growth of M. aeruginosa under laboratory conditions. The inhibition percentages after 24 h, 48 h, 72 h and 96 h exposure at the concentration of 1 mg/L were 8.13%, 16.49%, 39.56% and 55.31%, respectively. The activities of superoxide dismutase (SOD), catalase (CAT), and the concentrations of malondialdehyde (MDA) in M. aeruginosa were stimulated by doxycycline hydrochloride after 24 h exposure under a series of concentrations. The results are useful for environmental assessment of antibiotics. Besides, it is also helpful for guiding the application of doxycycline hydrochloride in agricultural settings.