title: Influence of coexisting spiramycin contaminant on the harm of Microcystis aeruginosa at different nitrogen levels.
abstract: The influence of nitrogen on the effects of the antibiotic contaminant spiramycin on Microcystis aeruginosa was studied through a 7-day exposure test. At current contamination levels of 0.5-100 mg L(-1) for nitrogen and 0.1-0.4 μg L(-1) for spiramycin, the two factors significantly interacted with each other (p<0.05) on the synthesis of chlorophyll-a and protein, the production and release of microcystins as well as the expression of ntcA gene and mcyB gene in M. aeruginosa. Nitrogen significantly affected the toxicity of spiramycin on algal growth (p<0.05) via regulation of protein synthesis. The photosynthesis system including chlorophyll-a, the psbA gene, and the rbcL gene participated in stress responses to spiramycin. Coexisting spiramycin contaminant increased the harm of M. aeruginosa by stimulating the production and release of MCs at a nitrogen level of 0.5 mg L(-1), but alleviated M. aeruginosa pollution at higher nitrogen levels of 5-100 mg L(-1) by inhibiting algal growth, the production of microcystins and the expression of ntcA and mcyB. The nitrogen-dependent effects of spiramycin should be considered in the control of M. aeruginosa bloom in the presence of spiramycin.
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, PR China. Electronic address: liuying2010@sdu.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, PR China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: Shandong Urban and Rural Planning Design Institute, Jinan 250013, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Chen
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, PR China.
authors.forename: Baoyu
authors.initials: B
authors.lastname: Gao
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D052998:Microcystins / Q000378:metabolism; D046931:Microcystis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D009584:Nitrogen / Q000494:pharmacology; D015572:Spiramycin / Q000494:pharmacology*; D014874:Water Pollutants, Chemical / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D052998:Microcystins; D014874:Water Pollutants, Chemical; D015572:Spiramycin; D009584:Nitrogen
keywords: Algal growth; Combined pollution; Microcystins; Photosynthesis; Stress response