摘要
恩诺沙星是医药及水产养殖业广泛使用的喹诺酮类抗生素,是我国地表水中残留量较多的抗生素种类之一;然而有关该抗生素对水体中浮游植物毒理作用以及后者对其去除作用的研究还鲜见报道.本研究以绿藻门的胶网藻(Dictyosphaerium sp.)为对象,通过12 d室内培养实验,分析在不同浓度(0、5、25、50和100 mg·L^-1)恩诺沙星暴露的条件下,胶网藻的生长、光合作用活力和胞外多糖的响应变化及其对不同浓度恩诺沙星的去除效率.结果表明,各处理组中胶网藻的生物量和光合色素含量均随培养时间的增加而升高,但与对照组相比,恩诺沙星对胶网藻的生长和光合色素积累均产生显著抑制作用(P<0.01).通过拟合分析,计算出恩诺沙星对胶网藻96 h半数致死浓度(LC50)为(241.29±7.33)mg·L^-1,表明胶网藻能够适应高浓度的恩诺沙星胁迫.同时发现,当恩诺沙星浓度<5 mg·L^-1时,能够促进胶网藻的最大光合速率(Fv/Fm),但浓度>5 mg·L^-1时则对胶网藻具有抑制作用(P<0.01);实际光合速率(Yeild)和最大电子传递速率(ETRmax)在12 d内呈现先降后升的变化趋势,胶网藻在6 d后可逐渐适应胁迫环境而恢复一定的光合活力.此外,恩诺沙星可刺激胶网藻释放胞外多糖,水溶性多糖(RPS)和胞外胶鞘多糖(CPS)含量均随恩诺沙星浓度升高而增加.实验结束时,4个无藻对照组(5、25、50和100 mg·L^-1)中恩诺沙星的去除率分别为7.27%、5.56%、5.30%和4.88%,而添加胶网藻的处理组其去除率分别为对照组的3.21、3.01、2.69和2.83倍,表明胶网藻对于恩诺沙星的去除具有显著的促进作用(P<0.01).本研究结果为理解喹诺酮类抗生素对水体初级生产者的生态毒性提供了新资料,同时也为水体抗生素残留的生态去除和淡水微藻的生物资源化利用提供了新的思路.
Enrofloxacin(ENR),a fluoroquinolones antibiotic,is widely used in the medical and aquaculture fields.Its residues in surface waters in China are high.However,few studies have evaluated both its toxicity to phytoplankton and the degradation or removal by microalgae.In this study,the growth,photosynthetic activity,and exopolysaccharides(EPS)of freshwater micro-green algae Dictyosphaerium sp.and the dynamics of ENR concentrations(0,5,25,50,and 100 mg·L^-1)were studied through an exposure experiment for 12 days.Results showed that the biomass and photosynthetic pigment content of Dictyosphaerium sp.increased with increasing exposure time in each treatment;however,it showed a significant inhibitory effect on the growth and pigment accumulation of Dictyosphaerium sp.compared with the control group(P<0.01).The LC50 of ENR to Dictyosphaerium sp.was(241.29±7.33)mg·L^-1 after 96-h exposure,indicating that Dictyosphaerium sp.could adapt to the stress conditions of high concentration ENR.Meanwhile,when the concentration of enrofloxacin was<5 mg·L^-1,it was found to promote the maximum photosynthetic rate(Fv/Fm)of Dictyosphaerium sp.On the contrary,when the concentration of enrofloxacin was>5 mg·L^-1,photosynthetic inhibition was observed(P<0.01).The actual photosynthetic rate(Yield)and the maximum electron transfer rate(ETRmax)showed a trend of initially decreasing and then increasing in 12 days.It can gradually adapt to the stress conditions and recover certain photosynthetic activity after 6 days’exposure.In addition,ENR can also stimulate the EPS(RPS and CPS)release.At the end of the experiment,the removal rates of ENR in the four control groups(no algae addition groups)(5,25,50,and 100 mg·L^-1ENR)were 7.27%,5.56%,5.30%,and 4.88%,respectively,while the removal rates of the treatment groups were 3.21,3.01,2.69,and 2.83 times of the no algae groups,indicating that Dictyosphaerium sp.had a significant promoting effect on the removal of ENR(P<0.01).Overall,our results can provide new insights for the understanding of the ecological toxicity of fluoroquinolone antibiotics to primary producers in the aquatic system and also provide new ideas for the ecological removal of antibiotic residues in water bodies and the biological resource utilization of freshwater microalgae.
作者
王振方
韩子玉
王梦雪
马逸驰
王婷
王丽卿
张玮
WANG Zhen-fang;HAN Zi-yu;WANG Meng-xue;MA Yi-chi;WANG Ting;WANG Li-qing;ZHANG Wei(Centre for Research on Environmental Ecology and Fish Nutrient(CREEFN)of the Ministry of Agriculture,Shanghai Ocean University,Shanghai 201306,China;Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources,Ministry of Education,Shanghai Ocean University,Shanghai 201306,China;National Demonstration Center for Experimental Fisheries Science Education,Shanghai Ocean University,Shanghai 201306,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2020年第6期2688-2697,共10页
Environmental Science
基金
国家水体污染控制与治理科技重大专项(2017ZX07207002)
上海市科委部分地方院校能力建设项目(19050501900)
上海海洋大学青年教师科研启动基金项目。
