恩诺沙星对小型模型水生态系统中底泥微生物的影响

兽药在环境中的行为及其生态效应已成为目前生态毒理学研究的热点之一。恩诺沙星是畜禽养殖业中广泛应用的抗菌药物，它可随畜禽排泄物进入环境，对环境生物产生影响。为对恩诺沙星的生态安全评价提供依据，利用小型模型水生态系统研究了恩诺沙星在其中的降解及其对底泥微生物数量的影响，于室外大棚以自然发生法构建了小型模型水生态系统（水生微宇宙），培育2个月待其稳定后用于试验研究。试验设恩诺沙星0．02、0．05、O．1、0．2和0．5mg·L^-1 5个浓度系列，1个空白对照。结果表明，试验初期恩诺沙星在模型水生生态系统中的消失速度很快，随时间推移消失速度逐步减慢，并且在低浓度时维持较长的时间；初始浓度越高，恩诺沙星在低浓度时维持的时间越久。在试验浓度范围内，恩诺沙星对淤泥中的好氧细菌、真菌、放线菌、氨化细菌和硝化细菌的数量均无显著影响。

Effects of Enrofloxacin on Microorganisms of Silt in Aquatic Microcosms

Environmental behaviors and ecological effects of veterinary drug had been an increasingly hot topic in ecotoxicology. Considered as a most important antibiotic, enrofloxacin was widely applied to promote livestock production. However, enrofloxacin normally excreted into manure could adversely affect organisms of the surroundings. Degradation and impacts on silt microorganisms of enrofloxacin were determined in aquatic microcosms to evaluate ecological risk of antibiotics. Six of aquatic microcosms were successfully set up in natural conditions and applied for testing. Levels of enrofloxacin were designed to be 0, 0.02, 0.05, 0.1, 0.2 and 0.5 mg· L^-1 respectively for determining. The concentration of enrofloxacin and its metabolite ciprofloxacin in water samples were measured by high-performance liquid chromatography （HPLC）. The population of aerobic bacteria, fungus, actinomycetes, ammonifying bacteria and nitrifying bacteria in silt were determined by plate cultivation method. The results showed that enrofloxacin was rapidly degraded in the initial stage in aquatic microcosms. Degradation of enrofloxacin slowed down afterwards and enrofloxacin maintained in low concentration for a long time. It was observed that the higher concentration of antibiotic was in initial stage, the longer time low level maintained in. 0.02~0.5 mg· L^-1 enrofloxacin had no significant effects on the population of aerobic bacteria, fungus, actinomycetes, ammonifying bacteria and nitrifying bacteria in this experiment. Ecological effects of enrofloxacin on silt microorganism in aquatic ecosystem were finally discussed in the paper. It suggested that the molecular biological method should be adopted to assess the effects of veterinary drug on environmental microorganisms.