Assessing the effect of high doses of ampicillin on five marine and freshwater phytoplankton species: a biodegradation perspective

Previous studies have identified several effects of antibiotic exposure at doses typically found in natural water (~μg). However, high doses of antibiotics can be found near wastewater treatment plants, and antibiotic concentrations in natural watercourses are likely to increase due to continuous current inputs. Therefore, the systematic evaluation of the susceptibility of phytoplankton species to antibiotics in water should be conducted for an improved risk assessment and the development of biotechnology for antibiotic residue management. The aim of the present study was, therefore, to investigate the response to high concentrations of ampicillin in several microalgae and cyanobacteria species with consideration of potential biodegradation applications for industrial and sanitary wastewaters. Pure laboratory cultures of freshwater (Dictyosphaerium chlorelloides, Chlamydomonas reinhardtii and Microcystis aeruginosa) and marine (Emiliania huxleyi and Prochloron sp.) species were exposed to several doses of ampicillin (6–14 mg L⁻¹). Cell growth and other functions were followed in each species for up to a month. The results revealed that the species susceptibility to ampicillin varied greatly. No effect was observed in the chlorophytes, M. aeruginosa presented high inhibition and microcystin stimulation, upregulation/enhancement occurred in E. huxleyi, and photochemical stress occurred in the marine cyanobacterium Prochloron sp. Moreover, we observed that the ampicillin effect varied over time in susceptible species. Despite the variability of response, all the species presented high rates of antibiotic degradation. From these bioassays, it can be inferred that the effect of ampicillin cannot be generalized to microalgae groups. Additionally, the potential of microalgae to mitigate antibiotic impacts by degradation is a novel aspect yet to be investigated.