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

Enrofloxacin (ENR), a fluoroquinolone antibiotic, has gained big scientific concern due to its ecotoxicity on aquatic microbiota. The ecotoxicity and removal of ENR by five individual microalgae species and their consortium were studied to correlate the behavior and interaction of ENR in natural systems. The individual microalgal species (Scenedesmus obliquus, Chlamydomonas mexicana, Chlorella vulgaris, Ourococcus multisporus, Micractinium resseri) and their consortium could withstand high doses of ENR (≤1 mg L-1). Growth inhibition (68-81%) of the individual microalgae species and their consortium was observed in ENR (100 mg L-1) compared to control after 11 days of cultivation. The calculated 96 h EC50 of ENR for individual microalgae species and microalgae consortium was 9.6-15.0 mg ENR L-1. All the microalgae could recover from the toxicity of high concentrations of ENR during cultivation. The biochemical characteristics (total chlorophyll, carotenoid, and malondialdehyde) were significantly influenced by ENR (1-100 mg L-1) stress. The individual microalgae species and microalgae consortium removed 18-26% ENR at day 11. Although the microalgae consortium showed a higher sensitivity (with lower EC50) toward ENR than the individual microalgae species, the removal efficiency of ENR by the constructed microalgae consortium was comparable to that of the most effective microalgal species.