利用全细胞微生物传感器研究四环素的典型环境行为对细菌抗性基因表达的影响及机理

Antibiotic residues in the environment could exert selective pressure on indigenous bacteria to develop antibiotic resistance, bringing the potentially adverse impact on the ecological environment and human health. Tetracyclines are the class of antibiotics most widely utilized for livestock production, they have been detected in different environmental compartments at high levels. But little is known about the potential influence factors that change the induction process and degree of tetracycline residues in water and soil to bacteria for expressing antibiotic resistance gene. This project will use a genetically modified tetracycline responsive whole-cell biosensor as representative bacteria to both detect and quantify the bioavailability and the selective pressure of tetracycline in water and soil to bacteria. The influences of tetracycline adsorbing on soil particles, its photolysis and hydrolysis, as well coexisting with different natural phenolic acids on tetracycline induction degree to bacteria for expression of antibiotic resistance gene will be explored. This project will clarify the influences and mechanisms of tetracycline’s typical environmental behaviors on its induction to biosensor for the expression of antibiotic resistance gene. The results obtained will be of great significance to understand the origins of tetracycline resistant bacteria and genes in soil and water environment and to evaluate the environmental risk of tetracyclines.

环境中残留的抗生素可诱导细菌产生抗生素抗性，该生物过程对生态环境和人体健康的影响或不可忽略。四环素作为目前使用量最大、应用范围最广的一类抗生素，其已在不同的环境介质中被检出。然而目前有关环境残留四环素对细菌抗性基因表达的诱导过程，以及该过程的影响因素、作用机制等仍缺乏系统的研究和有效的数据支撑。本项目拟以四环素可诱导其发光的全细胞微生物传感器作为供试微生物，企图快速、准确地探究环境介质中的四环素对细菌抗性基因表达的诱导作用，并着重分析四环素的吸附、光解、水解以及与常见天然有机酚酸化合物共存时对四环素诱导细菌抗性基因表达的影响及机制。该研究对于揭示环境中四环素耐药细菌及抗性基因的来源以及评价四环素的环境生态危害具有重要意义。

四环素作为广泛使用的一类抗生素，其已在不同的环境中被检出。然而目前有关环境残留四环素对细菌的生物可利用性及其影响因素还缺乏系统研究。通过使用四环素可诱导发光的全细胞微生物传感器作为表征其生物可利用性大小的工具，本项目发现了土壤吸附的四环素首先可以解析出来被细菌利用且表现出了低浓度的四环素可以被更多的细菌所利用，其次细菌也可以生长在土壤颗粒物表面直接利用吸附态的四环素。盐渍化作为重要的土壤环境问题，本项目也发现了高浓度的NaCl增加了全细胞生物传感器对固体培养基中四环素的利用度，其机制为高浓度的盐增加了细胞膜的通透性，结果促进了细胞对四环素的吸收。此外，项目也揭示了天然水体中四环素类抗生素的昼夜光化学行为，阐明了四环素代谢物的黑暗转化机制。以上研究结果对于理解四环素的环境行为过程及其生态风险具有重要意义。