Bioavailability of Tetracycline in Water and Soil to Bacteria for Expressing Antibiotic Resistance Response

水和土壤中四环素对细菌表达抗生素耐药性反应的生物利用度

• 批准号: 1438105
• 负责人: Hui Li
• 金额: $ 32.84万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-10-01 至 2018-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1438105&HistoricalAwards=false
• 关键词: Bioavailability; Tetracycline; Water; Soil; Bacteria

1438105LiBioavailability of Tetracycline in Water and Soil to Bacteria for Expressing Antibiotic Resistance ResponseTetracyclines are the most common group of antibiotics for livestock and people, and the proliferation of tetracycline-resistant bacteria has become an ever-increasing global threat to human health. Tetracyclines are widely distributed in water and soils, where they exert selective pressure on indigenous microbial communities. A prerequisite for development of antibiotic resistance is bacterial uptake of tetracycline, but little is known about the relative bioavailabilities to bacteria of the many possible aqueous and sorbed tetracycline forms. The concurrent increases in environmental tetracyclines and antibiotic resistance genes suggest that trace amounts of tetracycline exert selective pressure on indigenous microbial communities. However, no relationships have been demonstrated at the primary nexuses of tetracyclines and bacteria, such as wastewater treatment plants or animal feeding facilities. The proposed project attacks a pressing social problem, the threats to the efficacy of antibiotics. The unifying concept of bioavailability in this project integrates environmental and analytical chemistry with microbial ecology. All students and postdocs develop multiple complementary experimental approaches and disciplinary perspectives. Women and underrepresented groups are encouraged at all levels, including work-study undergraduates and interns. Results and approaches will be presented in multiple graduate and undergraduate courses, and disseminated more widely through PIs involvement in international and multi-state working groups, multiple departments, centers, and grants. The PIs have two synergistic research projects, one on transport of antibiotics from soils to surface water by runoff, and one on bioavailability of dioxins which are strongly sequestered by soils. Due to the projects broad social relevance, opportunities for environmental education and outreach are promising for the public and K-12, regulators, and practitioners, and will be pursued by the PIs in conjunction with MSU Extension.This proposal seeks to develop a mechanistic understanding of the effect of tetracycline speciation (among its sorbed and aqueous species) on the development of antibiotic resistance in natural and engineered systems. The PIs hypothesize that; a) certain aqueous tetracycline species will be preferentially bioavailable to bacteria, and, b) tetracycline sequestration in soil geosorbents will limit its bioavailability. An E. coli bioreporter constructed by transcriptional fusions between a tetR-regulated tetracycline-inducible promoter and green fluorescent protein will be used in this study. In each experiment, the project team will measure intracellular concentrations of tetracycline in the bioreporter and also estimate the expression of antibiotic resistance by quantifying bioreporter fluorescence. Specific aims are: (1) to identify the tetracycline species that optimizes bioavailability and activation of antibiotic resistance genes in aqueous solutions, (2) to evaluate the bioavailabilities of tetracycline sorbed to whole soils and soil components, and, (3) to determine the expression of antibiotic resistance evoked by sorbed tetracycline as functions of soil water content, biofilm formation on geosorbent surfaces, and potential uptake of sorbent particles by bacterial cells. The PIs hypothesize that bacterial tetracycline resistance is not a simple function of total tetracycline concentration, but instead depends on the detailed environmental speciation of the antibiotic. The PIs propose to discover such speciation linkages. This project will advance the mechanistic knowledge of tetracycline uptake by bacteria as functions of biogeochemical factors (pH, metal cations, and natural organic ligands), tetracycline sorption to various geosorbents, soil moisture content, and biofilm formation. Data will be used in chemical speciation modeling to identify the preferentially bioavailable tetracycline species that maximize the development of antibiotic resistance in E. coli. This improved mechanistic understanding of biogeochemical controls on the induction of antibiotic resistance should allow the rational development of improved environmental waste management schemes. For example, liming before waste application would increase aqueous Ca2+ and pH, which both may suppress the bioavailability of tetracyclines to bacteria. Furthermore, in-situ sorbent amendments such as biochar may sequester tetracycline, decrease bioavailability, and thereby diminish natural selection for antibiotic resistance.

1438105 Li水和土壤中四环素对细菌的生物利用度，以表达抗生素耐药性反应四环素是牲畜和人最常见的抗生素组，四环素耐药细菌的增殖已成为对人类健康日益严重的全球威胁。四环素广泛分布于水和土壤中，它们对本地微生物群落施加选择性压力。抗生素耐药性发展的先决条件是细菌对四环素的摄取，但对许多可能的水性和吸附的四环素形式对细菌的相对生物利用度知之甚少。环境中四环素和抗生素耐药基因的同时增加表明，痕量四环素对土著微生物群落产生选择性压力。然而，在四环素和细菌的主要联系中，如废水处理厂或动物饲养设施，没有关系得到证明。该项目旨在解决一个紧迫的社会问题，即对抗生素功效的威胁。在这个项目中，生物利用度的统一概念将环境和分析化学与微生物生态学相结合。所有的学生和博士后发展多种互补的实验方法和学科观点。鼓励妇女和代表性不足的群体在各级工作，包括半工半读的本科生和实习生。结果和方法将在多个研究生和本科生课程中展示，并通过参与国际和多国工作组，多个部门，中心和赠款的PI更广泛地传播。研究所有两个协同研究项目，一个是关于抗生素通过径流从土壤转移到地表水的问题，另一个是关于二恶英的生物利用率问题，二恶英在土壤中具有很强的螯合作用。由于该项目广泛的社会相关性，环境教育和推广的机会是有希望的公众和K-12，监管机构和从业人员，并将与MSU Extension.This提案寻求开发四环素形态（在其吸附和水的物种）对自然和工程系统中抗生素耐药性的发展的影响的机械理解。PI假设：a）某些含水四环素物质将优先被细菌生物利用，和，B）土壤地质吸附剂中的四环素螯合将限制其生物利用度。大肠在本研究中将使用由tetR调节的四环素诱导型启动子和绿色荧光蛋白之间的转录融合构建的大肠杆菌生物报告基因。在每个实验中，项目团队将测量生物报告物中四环素的细胞内浓度，并通过定量生物报告物荧光来估计抗生素耐药性的表达。具体目标是：（1）鉴定优化水溶液中抗生素抗性基因的生物利用度和活化的四环素种类，（2）评估吸附到整个土壤和土壤组分的四环素的生物利用度，和（3）确定由吸附的四环素引起的抗生素抗性的表达作为土壤含水量、地质吸附剂表面上的生物膜形成、以及细菌细胞对吸附剂颗粒的潜在吸收。PI假设细菌四环素耐药性不是总四环素浓度的简单函数，而是取决于抗生素的详细环境形态。 PI建议发现这种物种形成的联系。该项目将推进四环素细菌吸收的机理知识，作为生物地球化学因素（pH值，金属阳离子和天然有机配体），四环素吸附到各种地质吸附剂，土壤水分含量和生物膜形成的函数。数据将用于化学形态建模，以确定优先生物可利用的四环素物种，最大限度地提高抗生素耐药性的发展在大肠杆菌。杆菌这种对生物化学控制诱导抗生素耐药性的机制的理解的提高，应该允许合理开发改进的环境废物管理计划。例如，在废物施用之前加石灰会增加水溶液的Ca 2+和pH，这两者都可能抑制四环素类药物对细菌的生物利用度。此外，原位吸附剂改良剂如生物炭可能会螯合四环素，降低生物利用度，从而减少抗生素耐药性的自然选择。