肠道病原菌的抗性基因、毒力基因在污泥厌氧消化过程中的转归与去除机制

Pathogens could capture antibiotic resistance genes (ARGs) and virulence genes (VGs) through horizontal gene transfer during sewage sludge treatment processes, therefore enhance their antibiotic resistance and pathogenicity result in posing risk to human health. However, there are lack of research relating to antibiotic resistance, ARGs and VGs in pathogens of sewage sludge treatment both for domestic and overseas researchers. Therefore, this research project would take Escherichia coli and Enterococci as study objects which are the common intestinal pathogens in sewage sludge. The fate of ARGs, VGs in Escherichia coli and Enterococci and tof sewage sludge during ananerobic digestion in a full-scale wastewater treatment plant would be examined. Their antibiotic resistance would also be investigated. Moreover, the removal of ARGs, VGs and declination of antibiotic resistance in enhanced ananerobic digestion processes would be studied, and process optimization would be performed in order to find the available sewage sludge treatment process that can enhance sludge anaerobic digestion effect and inhibit the antibiotic resistance and pathogenicity of intestinal pathogens. The inherent links between ARGs, VGs during sludge anaerobic digestion and their influence to antibiotic resistance would be analyzed. Furthermore, the influence factors and removal mechanism of ARGs、VGs in Escherichia coli and Enterococci would be discussed. The purpose of this project is to provide reasonable scientific basis and technical support for the control of antibiotic resistance and pathogenicity of pathogens during sewage sludge treatment.

城市污泥处理过程中病原菌可以通过基因水平转移获得抗性基因(antibiotic resistance genes, ARGs)与毒力基因(virulence genes, VGs)，从而增强耐药性与致病性，严重威胁人类健康。然而目前国内外缺乏对城市污泥厌氧消化过程中病原菌耐药性、携带的ARGs与VGs的研究，因此本课题以城市污泥中常见的肠道病原菌——大肠杆菌、肠球菌为研究对象，考察其携带的ARGs与VGs在城市污泥厌氧消化过程中的分布与转归及耐药性的变化；重点考察ARGs、VGs与耐药性在强化厌氧消化工艺过程中的削减效果，并优化工艺参数，探索既可以增强厌氧消化效果又能够控制抗性污染与致病性细菌传播的污泥处理工艺；解析厌氧消化过程中ARGs、VGs之间的内在联系及对细菌耐药性的影响；探讨ARGs、VGs的影响因素与去除机制，为控制城市污泥中肠道病原菌的耐药性与致病性提供科学依据与技术支撑。

城市污泥中含有大量肠道病原菌，可携带多种抗生素抗性基因(Antibiotic resistance genes, ARGs)及毒力基因(Virulence genes, VGs)，具有传播潜在耐药性和致病性的危险。本项目针对不同污泥高级厌氧消化过程中，肠道病原菌的耐药性、ARGs、VGs及内在联系进行研究，结果表明：.无论是实际污水厂污泥热水解-中温厌氧消化工艺，还是小试规模的高温好氧、微波预处理强化中温厌氧消化工艺，预处理可削减肠球菌的抗生素耐药率、ARGs和VGs检出率，虽然中温厌氧消化后肠球菌对某些抗生素耐药率、部分ARGs、VGs检出率有所增加，但有预处理的中温厌氧消化工艺比没有预处理的工艺对肠球菌的潜在耐药性和致病性控制效果更佳。污泥中携带VGs的肠球菌对阿奇霉素的耐药率较高；此外，携带VGs的肠球菌可携带多种ARGs；这些特征肠球菌的检出率均在预处理后降低，厌氧消化后增加。遗传元件(Mobile genetic elements, MGEs)对肠球菌的潜在耐药性和致病性密切相关，厌氧消化后肠球菌中遗传元件（如Tn916/1545）及其与ARGs和VGs共检出率的增加，是导致肠球菌耐药性和潜在致病性增加的重要原因。.预处理工艺中，热水解对污泥产甲烷效果促进作用最佳。进一研究表明，水解污泥在40℃中温、55℃高温厌氧消化工艺相比，虽然高温厌氧对肠球菌数量和耐药率的削减效果更高，中温厌氧对肠球菌中ARGs及Tn916/1545检出率、以及ARGs与VGs共现率的削减效果更好，并有更高的甲烷产量，因此污泥热水解-中温厌氧消化是最有利于污泥能源化及抗性污染控制的处理工艺。.污泥基因组DNA中ARGs的绝对和相对丰度变化规律与肠球菌中ARGs的规律相似，均呈现预处理后降低，厌氧消化后反弹。MGEs是污泥处理过程中ARGs归趋的主要驱动因素，而降低古菌/细菌的生物量、生物多样性、污泥的氨氮浓度有助于控制ARGs的传播。.本研究结果可为人们进一步了解污泥处理过程中肠道病原菌的潜在致病性和耐药性的变化规律、内在联系及削减机制提供了丰富的理论基础，并为今后城市污水厂污泥选择既可强化厌氧消化、又有利于抗性污染控制的处理工艺提供了坚实的科学依据。.