Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i>
<b>Background:</b> 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 trans...
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MDPI AG
2025-04-01
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| Series: | Antibiotics |
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| Online Access: | https://www.mdpi.com/2079-6382/14/5/448 |
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| author | Temilola O. Olanrewaju James S. G. Dooley Heather M. Coleman Chris McGonigle Joerg Arnscheidt |
| author_facet | Temilola O. Olanrewaju James S. G. Dooley Heather M. Coleman Chris McGonigle Joerg Arnscheidt |
| author_sort | Temilola O. Olanrewaju |
| collection | DOAJ |
| description | <b>Background:</b> 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 <i>Tetrahymena pyriformis</i> facilitates the transfer of antibiotic resistance genes between <i>Enterococcus faecalis</i> strains. <b>Methods</b>: Conjugation assays were conducted under laboratory conditions using a <i>vanA</i>-carrying donor and a rifampicin-resistant recipient at an initial bacterial concentration of 10<sup>9</sup> CFU/mL and ciliate density of 10<sup>5</sup> N/mL. <b>Results</b>: 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, <i>vanA</i> gene transfer frequency was highest at 24 h (10<sup>−4</sup>–10<sup>−5</sup> CFU/mL), and the presence of energy sources increased gene transfer frequency by one order of magnitude. <b>Conclusions</b>: These findings suggest that ciliate grazing may contribute to <i>vanA</i> gene transfer in WWTP effluents, potentially facilitating its dissemination among permissive bacteria. Given the ecological and public health risks associated with <i>vanA</i> gene persistence in wastewater systems, understanding protozoan-mediated gene transfer is crucial for mitigating the spread of antibiotic resistance in aquatic environments. |
| format | Article |
| id | doaj-art-706ce6d3cb374ffeba4f55d295ee9193 |
| institution | DOAJ |
| issn | 2079-6382 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Antibiotics |
| spelling | doaj-art-706ce6d3cb374ffeba4f55d295ee91932025-08-20T03:14:32ZengMDPI AGAntibiotics2079-63822025-04-0114544810.3390/antibiotics14050448Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i>Temilola O. Olanrewaju0James S. G. Dooley1Heather M. Coleman2Chris McGonigle3Joerg Arnscheidt4School of Geography and Environmental Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UKNutrition Innovation Centre for Food and Health (NICHE), School of Biomedical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UKSchool of Pharmacy and Pharmaceutical Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UKSchool of Geography and Environmental Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UKSchool of Geography and Environmental Sciences, Ulster University, Cromore Road, Coleraine BT52 1SA, UK<b>Background:</b> 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 <i>Tetrahymena pyriformis</i> facilitates the transfer of antibiotic resistance genes between <i>Enterococcus faecalis</i> strains. <b>Methods</b>: Conjugation assays were conducted under laboratory conditions using a <i>vanA</i>-carrying donor and a rifampicin-resistant recipient at an initial bacterial concentration of 10<sup>9</sup> CFU/mL and ciliate density of 10<sup>5</sup> N/mL. <b>Results</b>: 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, <i>vanA</i> gene transfer frequency was highest at 24 h (10<sup>−4</sup>–10<sup>−5</sup> CFU/mL), and the presence of energy sources increased gene transfer frequency by one order of magnitude. <b>Conclusions</b>: These findings suggest that ciliate grazing may contribute to <i>vanA</i> gene transfer in WWTP effluents, potentially facilitating its dissemination among permissive bacteria. Given the ecological and public health risks associated with <i>vanA</i> gene persistence in wastewater systems, understanding protozoan-mediated gene transfer is crucial for mitigating the spread of antibiotic resistance in aquatic environments.https://www.mdpi.com/2079-6382/14/5/448antimicrobial resistanceantibiotic resistant bacteriahorizontal gene transferconjugationprotistsprotozoa |
| spellingShingle | Temilola O. Olanrewaju James S. G. Dooley Heather M. Coleman Chris McGonigle Joerg Arnscheidt Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i> Antibiotics antimicrobial resistance antibiotic resistant bacteria horizontal gene transfer conjugation protists protozoa |
| title | Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i> |
| title_full | Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i> |
| title_fullStr | Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i> |
| title_full_unstemmed | Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i> |
| title_short | Bacterivorous Ciliate <i>Tetrahymena pyriformis</i> Facilitates <i>vanA</i> Antibiotic Resistance Gene Transfer in <i>Enterococcus faecalis</i> |
| title_sort | bacterivorous ciliate i tetrahymena pyriformis i facilitates i vana i antibiotic resistance gene transfer in i enterococcus faecalis i |
| topic | antimicrobial resistance antibiotic resistant bacteria horizontal gene transfer conjugation protists protozoa |
| url | https://www.mdpi.com/2079-6382/14/5/448 |
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