Hormesis effects of amoxicillin on growth and cellular biosynthesis of Microcystis aeruginosa at different nitrogen levels.
Coexisting antibiotic contaminants have potential to regulate cyanobacterial bloom, and the regulation is likely affected by nitrogen supply. A typical cyanobaterium Microcystis aeruginosa was cultured with 0.05-50 mg L(-1) of nitrogen and exposed to 100-600 ng L(-1) of amoxicillin for 7 days. Algal growth was not significantly (p > 0.05) affected by amoxicillin at the lowest nitrogen level of 0.05 mg L(-1), stimulated by 600 ng L(-1) of amoxicillin at a moderate nitrogen level of 0.5 mg L(-1) and enhanced by 100-600 ng L(-1) of amoxicillin at higher nitrogen levels of 5-50 mg L(-1). Amoxicillin affected chlorophyll-a, psbA gene, and rbcL gene in a similar manner as algal growth, suggesting a regulation of algal growth via the photosynthesis system. At each nitrogen level, synthesis of protein and polysaccharides as well as production and release of microcystins (MCs) increased in response to environmental stress caused by amoxicillin. Expression of ntcA and mcyB showed a positive correlation with the total content of MCs under exposure to amoxicillin at nitrogen levels of 0.05-50 mg L(-1). Nitrogen and amoxicillin significantly (p < 0.05) interact with each other on the regulation of algal growth, synthesis of chlorophyll-a, production and release of MCs, and expression of ntcA and mcyB. The nitrogen-dependent stimulation effect of coexisting amoxicillin contaminant on M. aeruginosa bloom should be fully considered during the combined pollution control of M. aeruginosa and amoxicillin.
Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, 250100, Jinan, People's Republic of China, alieen_1118@sina.com.
Ying
Y
Liu
Xiao
X
Chen
Jian
J
Zhang
Baoyu
B
Gao
D000658:Amoxicillin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D059165:Hormesis; D046931:Microcystis / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000658:Amoxicillin; D009584:Nitrogen