土霉素对厌氧发酵过程古菌群落及抗性基因的影响
发布时间：2018-08-08 16:36
【摘要】：抗生素因其具有防病、促生长的作用被广泛应用于畜禽养殖业。但是,大部分抗生素会随畜禽粪便排出。如果用含有抗生素的畜禽粪便进行厌氧发酵会对此过程产生一定的影响。中国畜禽养殖业主要使用四环素类抗生素(四环素,金霉素和土霉素),其中有关四环素和金霉素研究较多,土霉素研究较少。本研究采用小型厌氧发酵装置,通过外源添加不同浓度土霉素,以此来探究土霉素对于厌氧发酵过程中甲烷产量,酶活性,微生物群落多样性,四环素类抗性基因的影响以及土霉素在厌氧发酵过程中的含量变化。主要结果表明:1.土霉素对于甲烷累积产量、酶活性的影响以及土霉素的含量变化土霉素在厌氧发酵前期对于甲烷累积产量和脲酶活性有一定的促进作用,随后表现为抑制作用。对于脱氢酶活性,在厌氧发酵前期所有添加土霉素处理均表现为抑制作用,至厌氧发酵中期,低、中浓度土霉素对于脱氢酶的抑制作用解除。土霉素的含量变化表明,土霉素的去除主要在发生前30天,30天之后其含量基本维持不变。2.土霉素对古菌群落多样性的影响DGGE图谱表明土霉素对于古菌作用较小,测序结果表明,厌氧发酵系统中的优势古菌主要为甲烷粒状菌菌属中的菌种(Methanocorpusculum labreanum Z)甲烷丝状菌属中的菌种(Methanosaeta concilii GP-6),中温厌氧发酵对于不动杆菌(Acinetobacter sp)这类致病微生物有一定的去除作用。扫描电镜结果表明,厌氧发酵系统中的菌群主要以短杆菌、球状菌为主,同时有少量丝状菌。3.土霉素对四环素类抗性基因的影响共检出四种四环素类抗性基因,分别属于核糖体保护蛋白保护基因(tet(M)、tet(Q)、tet(W))和外排泵基因(tet(C)),其中核糖体保护蛋白基因丰度均高于外排泵基因。低、中浓度土霉素处理对于四环素类抗性基因(除tet(W))的去除率均高于对照处理,高浓度土霉素处理去除效果最差。抗性基因的丰度变化可能与抗性基因宿主微生物的数量变化有关。厌氧处理不利于去除四环素类抗性基因,厌氧发酵产物需进一步处理以降低抗性基因对于环境带来的风险。
[Abstract]:Antibiotics are widely used in livestock and poultry breeding because of their disease prevention and growth-promoting effect. However, most antibiotics are excreted in animal feces. Anaerobic fermentation of animal manure containing antibiotics may have an effect on this process. Tetracycline antibiotics (tetracycline, chlortetracycline and oxytetracycline) are mainly used in livestock and poultry breeding in China, in which tetracycline and chlortetracycline are studied more than oxytetracycline. In this study, a small anaerobic fermenter was used to investigate the effects of oxytetracycline on methane production, enzyme activity and microbial community diversity during anaerobic fermentation by exogenous adding different concentrations of oxytetracycline. Effects of tetracycline resistance genes and changes of oxytetracycline content during anaerobic fermentation. The main result is: 1. Effects of oxytetracycline on methane accumulation, enzyme activity and the content of oxytetracycline, oxytetracycline promoted methane accumulation and urease activity in the early stage of anaerobic fermentation, followed by inhibition. The activity of dehydrogenase was inhibited by oxytetracycline at the early stage of anaerobic fermentation, and the inhibition of midconcentration oxytetracycline on dehydrogenase was removed from the middle stage of anaerobic fermentation. The change of the content of oxytetracycline showed that the content of oxytetracycline was basically unchanged after 30 days before the occurrence of oxytetracycline. The effects of oxytetracycline on the diversity of ancient bacteria communities showed that oxytetracycline had little effect on ancient bacteria, and sequencing showed that oxytetracycline had little effect on ancient bacteria. The dominant ancient bacteria in the anaerobic fermentation system were mainly the (Methanocorpusculum labreanum Z) species in the genus (Methanocorpusculum labreanum Z). The medium temperature anaerobic fermentation could remove the pathogenic microbes such as Acinetobacter (Acinetobacter sp) to a certain extent. The results of scanning electron microscope showed that the microflora in the anaerobic fermentation system was mainly composed of Bacillus brevis, bulbous bacteria, and a small amount of filamentous bacteria. Effects of oxytetracycline on tetracycline resistance genes, four tetracycline resistance genes were identified, which belonged to ribosomal protection protein protection gene (tet (M) et (Q) (W) and efflux pump gene (tet (C),. The abundance of ribosomal protection protein gene was higher than that of efflux pump gene. The removal rate of tetracycline resistance genes (except tet (W) in low and middle concentration oxytetracycline treatment was higher than that in control treatment, and the removal efficiency of high concentration oxytetracycline treatment was the worst. The variation of resistance gene abundance may be related to the quantity change of resistance gene host microorganism. Anaerobic treatment is not conducive to the removal of tetracycline resistance genes, anaerobic fermentation products need to be further treated to reduce the risk of resistance genes to the environment.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X172
本文编号：2172381
[Abstract]:Antibiotics are widely used in livestock and poultry breeding because of their disease prevention and growth-promoting effect. However, most antibiotics are excreted in animal feces. Anaerobic fermentation of animal manure containing antibiotics may have an effect on this process. Tetracycline antibiotics (tetracycline, chlortetracycline and oxytetracycline) are mainly used in livestock and poultry breeding in China, in which tetracycline and chlortetracycline are studied more than oxytetracycline. In this study, a small anaerobic fermenter was used to investigate the effects of oxytetracycline on methane production, enzyme activity and microbial community diversity during anaerobic fermentation by exogenous adding different concentrations of oxytetracycline. Effects of tetracycline resistance genes and changes of oxytetracycline content during anaerobic fermentation. The main result is: 1. Effects of oxytetracycline on methane accumulation, enzyme activity and the content of oxytetracycline, oxytetracycline promoted methane accumulation and urease activity in the early stage of anaerobic fermentation, followed by inhibition. The activity of dehydrogenase was inhibited by oxytetracycline at the early stage of anaerobic fermentation, and the inhibition of midconcentration oxytetracycline on dehydrogenase was removed from the middle stage of anaerobic fermentation. The change of the content of oxytetracycline showed that the content of oxytetracycline was basically unchanged after 30 days before the occurrence of oxytetracycline. The effects of oxytetracycline on the diversity of ancient bacteria communities showed that oxytetracycline had little effect on ancient bacteria, and sequencing showed that oxytetracycline had little effect on ancient bacteria. The dominant ancient bacteria in the anaerobic fermentation system were mainly the (Methanocorpusculum labreanum Z) species in the genus (Methanocorpusculum labreanum Z). The medium temperature anaerobic fermentation could remove the pathogenic microbes such as Acinetobacter (Acinetobacter sp) to a certain extent. The results of scanning electron microscope showed that the microflora in the anaerobic fermentation system was mainly composed of Bacillus brevis, bulbous bacteria, and a small amount of filamentous bacteria. Effects of oxytetracycline on tetracycline resistance genes, four tetracycline resistance genes were identified, which belonged to ribosomal protection protein protection gene (tet (M) et (Q) (W) and efflux pump gene (tet (C),. The abundance of ribosomal protection protein gene was higher than that of efflux pump gene. The removal rate of tetracycline resistance genes (except tet (W) in low and middle concentration oxytetracycline treatment was higher than that in control treatment, and the removal efficiency of high concentration oxytetracycline treatment was the worst. The variation of resistance gene abundance may be related to the quantity change of resistance gene host microorganism. Anaerobic treatment is not conducive to the removal of tetracycline resistance genes, anaerobic fermentation products need to be further treated to reduce the risk of resistance genes to the environment.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X172
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相关期刊论文 前2条
1 姚建华;牛德奎;李兆君;梁永超;张树清;;抗生素土霉素对小麦根际土壤酶活性和微生物生物量的影响[J];中国农业科学;2010年04期
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，本文编号：2172381
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