title: Cellular and transcriptional responses in Microcystis aeruginosa exposed to two antibiotic contaminants.
abstract: The responses of Microcystis aeruginosa under exposure to spiramycin and amoxicillin were investigated on both cellular and genetic levels through a 7-day exposure test. Algal growth was inhibited by spiramycin while promoted by amoxicillin at test concentrations of 0.6-1.8 μg L(-1), indicating a higher toxicity of spiramycin than amoxicillin. During the whole exposure period, the chlorophyll a content and expression levels of psbA, psaB, and rbcL were significantly inhibited by spiramycin at test concentrations of 1.2 and 1.8 μg L(-1) (p < 0.05) and stimulated by 0.6-1.8 μg L(-1) of amoxicillin (p < 0.05), with respective decreases of up to 26, 75, 72, and 82% compared to the control and respective increases of 20, 70, 135, and 55%. During the 4 to 7 days of exposure, the microcystin-LR content and expression levels of mcyB and grpE were reduced by up to 66, 47, and 72% in spiramycin-treated algal cells, respectively, and stimulated by up to 1.3-, 1.4-, and 1.5-folds in amoxicillin-treated algal cells, respectively. Elevated recA expression was only observed in 1.2 and 1.8 μg L(-1) of spiramycin-treated algal cells, indicating severe DNA damage due to the high toxicity. Target antibiotics were suspected to regulate the growth and microcystin-production in M. aeruginosa via the photosynthesis system.
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, 250100, People's Republic of China, liuying2010@sdu.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Baoyu
authors.initials: B
authors.lastname: Gao
mesh_terms: D000658:Amoxicillin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D052998:Microcystins / Q000187:drug effects / Q000378:metabolism; D046931:Microcystis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D015572:Spiramycin / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D052998:Microcystins; D014874:Water Pollutants, Chemical; C078588:microcystin; D015572:Spiramycin; D000658:Amoxicillin