Olanrewaju Temilola O, Dooley James S G, Coleman Heather M, McGonigle Chris, Arnscheidt Joerg
School of Geography and Environmental Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.
Nutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK.
Antibiotics (Basel). 2025 Apr 28;14(5):448. doi: 10.3390/antibiotics14050448.
Wastewater treatment plants (WWTPs) are hotspots for the emergence and spread of antibiotic resistance genes (ARGs). In activated sludge treatment systems, bacterivorous protozoa play a crucial role in biological processes, yet their impact on the horizontal gene transfer in Gram-positive enteric bacteria remains largely unexplored. This study investigated whether the ciliate facilitates the transfer of antibiotic resistance genes between strains. : Conjugation assays were conducted under laboratory conditions using a -carrying donor and a rifampicin-resistant recipient at an initial bacterial concentration of 10 CFU/mL and ciliate density of 10 N/mL. : Transconjugant numbers peaked at 2 h when experiments started with recipient bacteria harvested in the exponential growth phase, and at 24 h when bacteria were in the stationary phase. In both cases, gene transfer frequency was highest at 24 h (10-10 CFU/mL), and the presence of energy sources increased gene transfer frequency by one order of magnitude. : These findings suggest that ciliate grazing may contribute to gene transfer in WWTP effluents, potentially facilitating its dissemination among permissive bacteria. Given the ecological and public health risks associated with gene persistence in wastewater systems, understanding protozoan-mediated gene transfer is crucial for mitigating the spread of antibiotic resistance in aquatic environments.
污水处理厂是抗生素抗性基因（ARGs）出现和传播的热点。在活性污泥处理系统中，食细菌原生动物在生物过程中起着关键作用，但其对革兰氏阳性肠道细菌水平基因转移的影响在很大程度上仍未得到探索。本研究调查了纤毛虫是否促进菌株间抗生素抗性基因的转移。：在实验室条件下进行接合试验，使用携带抗生素的供体和耐利福平的受体，初始细菌浓度为10CFU/mL，纤毛虫密度为10N/mL。：当实验以指数生长期收获的受体细菌开始时，转接合子数量在2小时达到峰值；当细菌处于稳定期时，转接合子数量在24小时达到峰值。在这两种情况下，抗生素基因转移频率在24小时最高（10-10CFU/mL），并且能量源的存在使基因转移频率提高了一个数量级。：这些发现表明，纤毛虫捕食可能有助于污水处理厂废水中抗生素基因的转移，有可能促进其在易感细菌中的传播。鉴于与废水系统中抗生素基因持久性相关的生态和公共卫生风险，了解原生动物介导的基因转移对于减轻水生环境中抗生素抗性的传播至关重要。
