Title: Unravelling novel mechanisms of horizontal transfer of class 1 integrons in bacteria. Implications for the dissemination of antibiotic resistance.
Abstract:The distribution pattern of mobile genetic elements, such as class 1 integrons and transposons, suggests dissemination through horizontal gene transfer (Domingueset al., 2012a). However, the role of natural transformation in such dissemination has remained largely unexplored, and was addressed in this thesis.
Exposure of the naturally competent A. baylyi BD413 to different DNA sources resulted in acquisition of antibiotic resistance traits as well as entire class 1 integrons and transposons (Domingues et al., 2012b, 2012c). DNA incorporation in the recipient genome was independent of the genetic relatedness between species, and was associated with different mechanisms, including homologous recombination and transposition of transposons and composite-transposons. Additionally, natural transformation of class 1 integron-harbouring populations of competent bacteria revealed that interspecies exchange of gene cassettes by homologous recombination is highly efficient (Domingueset al., 2012c).
In conclusion, natural transformation provides a much broader capacity for horizontal acquisitions of genetic elements and resistance traits from divergent species than previously assumed.
Acknowledgments: Centre of Pharmaceutical Studies, Faculty of Pharmacy, University of Coimbra, Portugal; Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, Norway; Personal grants: FCT (SFRH/BD/49061/2008) and Research Council of Norway (YGGDRASIL fellowship).
Domingues S, Da Silva GJ, Nielsen KM. (2012a), Integrons: Vehicles and pathways for horizontal dissemination in bacteria. Mob Genet Elements. 2, 211-223.
Domingues S, Nielsen KM, Da Silva GJ. (2012b), Various pathways leading to the acquisition of antibiotic resistance by natural transformation. Mob Genet Elements. 2, 257-260.
Domingues S, Harms K, Fricke WF, Johnsen PJ, da Silva GJ, Nielsen KM(2012c), Natural transformation facilitates transfer of transposons, integrons and gene cassettes between bacterial species. PLoS Pathog, 8:e1002837.
PhD degree: Pharmacy, specialization in Microbiology and Parasitology
Year of conclusion: 2013
Institution: Faculdade de Farmácia, Universidade de Coimbra
Supervision: Gabriela Jorge da Silva, (Faculdade de Farmácia, Universidade de Coimbra, Portugal) and Kaare Magne Nielsen (Department of Pharmacy, Romssa universitehta, University of Tromsø, Norway)