【作者】 姚志鹏；

【导师】 梁永超； 李兆君；

【作者基本信息】 中国农业科学院 ， 植物营养学， 2008， 硕士

【摘要】 随着畜牧业的发展,抗生素作为兽药被越来越广泛地应用于畜禽养殖业中。它在保障动物健康,促进畜牧业发展,改善人民生活水平等方面起了重要的作用。但是,兽药为人们带来诸多方便的同时,也造成了对人体健康和环境卫生的潜在危害,如兽药在动物性食品中的残留可导致人类变态(或过敏)反应、致畸、致突变和激素样作用等等。用药动物排至环境中的兽药及其代谢产物也会对人类生活的环境和生态系统产生影响。因此,除进行兽药对食品动物的药理毒理学研究外,亦应重视其对生态环境影响的研究,以求创造更安全、更适于畜牧业持续发展的优良生态环境。开展兽药对环境影响的研究是关系到人类健康和环境保护的重大课题。为此,我们通过室内微型模拟培养试验,并采用高效液相色谱等手段,对兽用抗生素土霉素的微生态环境效应进行了研究,同时还研究了土霉素在不同温度条件下降解特征。取得的主要研究结果如下:1.土霉素的生态毒理效应本试验研究了土霉素对我国两种有代表性的土壤(潮土和黑土)微生物活性的影响,结果表明,土霉素在土壤中有一定的生态风险,对土壤酶活性和土壤微生物生物量的影响较为复杂,且与其在土壤中的持留时间有关,具体表现为:(1)土霉素对土壤酶活性的影响。潮土脲酶活性表现为前期受到抑制,后期则受到刺激,而黑土脲酶活性在56天以前表现不明显(第1天100 mg OTC kg-1处理除外),56天以后表现为激活作用;潮土磷酸酶活性表现为前期受到刺激而后期则表现为抑制作用,黑土磷酸酶活性整体表现为前期以抑制作用为主,培养第112天则变现为低浓度时受到刺激和高浓度受到抑制;土霉素对潮土过氧化氢酶活性的影响表现为,整个培养期内均受到抑制,但是在后期随着培养时间的延长,过氧化氢酶活性受抑制的程度逐渐减弱,土霉素对黑土过氧化氢酶活性的影响与潮土相似;土霉素对潮土蔗糖酶活性的影响表现为,在培养第7、14、21、28、56天里,所有土霉素的处理,土壤蔗糖酶活性均低于对照,直到第112天蔗糖酶活性才恢复到对照的水平;土霉素对黑土蔗糖酶活性的影响在前期不明显,后期表现为强烈的抑制作用,直到培养结束这种抑制作用仍然存在;土霉素对潮土脱氢酶活性的影响在整个培养期间表现为刺激作用;土霉素对黑土脱氢酶活性的影响,在第28天前不明显,第28天后对脱氢酶活性具有刺激作用,第56天后则表现为抑制作用。(2)土霉素对土壤微生物生物量的影响。本试验条件下,土霉素对土壤微生物生物量及微生物生物量碳/氮的影响也与土霉素在土壤中的持留时间有关。具体表现为:培养第14至21天,土霉素对土壤微生物生物量影响较强烈,在培养第112天,土霉素对土壤微生物生物量的影响仍然存在。在培养后期,土霉素增加了土壤微生物生物量碳和氮的比率,表明土霉素可能会引起土壤微生物种群的改变。2.不同温度条件下土霉素的降解规律。土霉素在不同温度下降解速率是不同的,具体表现为:(1)土霉素在不同温度处理土壤中降解速率不同,25℃培养条件下降解速度明显快于4℃培养。土霉素在土壤中的降解符合一级动力学方程,不论是在25℃培养还是在4℃培养,其降解曲线均为幂指数方程,相关系数显著。更多还原

【Abstract】 With the development of stockbreeding, antibiotics are widely used in the animal and poultry production as veterinary drugs to protect animal and poultry from illness and to promote their growth. The usage of antibiotics in animal and poultry farms has been successful in improving farm animal production, promoting the development of animal husbandry, improving living standard and food security. However, veterinary drugs are potentially harmful to organisms in environments. For instance, veterinary drug residues in animal food can cause human allergy, malformation and mutation. Moreover, veterinary drug residues in environments can influence human life and ecosystem. Thus, in order to create a safe and clean environment, research objectives should be focused on not only the veterinary drugs pharmacology and toxicology, but also the influence of veterinary drugs on microorganisms in terrestrial ecological environments. In the present research, primary micro-ecological effects of oxytetracycline were evaluated by using incubation experiments and its degradation in soil under different temperature regimes was also investigated by means of HPLC. The main results were presented as follows:1.The micro-ecological effects of oxytetracycline in soilAn incubation experiment was conducted to study the micro-ecological effects of oxytetracycline in two representative soils in China (fluvo-aquic soil and black soil). The results showed that oxytetracycline posed some ecological risks in the soils. The effects of oxytetracycline on soil enzymes and microbial biomass were dependant on the retention time of oxytetracycline in soils.(1) The effects of oxytetracycline on soil enzymes. Urease activity was inhibited at early stages but were stimulated at later stages in fluvo-aquic soil tested, while it was unchanged before the 56- day in the black soil tested (except for the treatment with OTC at the level of 100 mg OTC kg-1 at the first day of incubation), and stimulated by OTC at the 112th day. Phosphatase activity was inhibited in fluvo-aquic soil tesed in the early stages and stimulated in the later stages. By contrast, phosphatase activity of black soil was restrained until the 112th day, and was stimulated with lower concentrations of OTC and restrained with higher concentrations of OTC. The activities of catalase were restrained in the whole culture periods, but were enhanced with increasing of culture time in both tested soils. The activity of sucrase in the fluvo-aquic soil treated with OTC was lower than that of the control treatment and was not recovered to the normal level until at the 112th day. However, in black soil, effects of OTC on activity of sucrase were not changed significantly within 28 days, and the enzyme activity was inhibited strongly afterwards. In general, the OTC added stimulated the activity of dehydrogenase in the fluvo-aquic soil. The activity of dehydrogenase in the black soil was not siginificantly affected by OTC before the 28th day and was stimulated until the 56th day, but was inhibited afterwards.(2) The effect of veterinary drug oxytetracycline on microbial biomass in soilUnder the experimental conditions, the effect of OTC on microbial biomass and carbon-nitrogen ratio (C/N) was dependent closely on the retention time of OTC in soil. The results showed that OTC significantly affected soil microbial biomass from the 14th day to the 21th day and such effect could be still observed at the 112th day. In addition, the addition of oxytetracycline could increase the ratio of soil microbial biomass carbon to soil microbial biomass nitrogen, suggesting that oxytetracycline might change the microbial community.2. Degradation of oxytetracycline under different temperature regimes.The degradation of oxytetracycline varied greatly from temperature regimes.(1) The degradation rate of oxytetracycline was quicker at 25℃than at 4℃. The degradation curve of oxytetracycline at 25℃or 4℃could be fitted into exponent equationswith correlation coefficient reached significantly level.更多还原