Integrons and conjugative elements are genetic elements frequently transferred among bacteria impacting deeply their biology. Notably, these elements play a major role in the capture and distribution of antibiotic resistance genes leading to public health issues. Both elements have been studied at the molecular level for more than 20 years. However, they were often described in light of their association with pathogens and the role they play in the spread and acquisition of antibiotic resistance, or virulence genes. Our understanding is thus biased toward these variants. The comprehension of their broader role have been hindered by the lack of tool or methodology to identify them precisely at large scale.
I will first present a tool allowing the precise identification of integrons despite their lack of sequence conservation, along with key results that were not anticipated.
In a second part I will tackle a broader evolutionary question related to mobile genetic elements in general. Precisely why some are integrated in the bacterial chromosome whereas others are extra-chromosomal ? I will focus on conjugative elements to address this question. To do so, I will present a method to identify conjugative elements along with another method to delimit those integrated in the chromosome. Finally, I will provide results highlighting differences and similarities between integrative and extra-chromosomal elements.