Project description: Plasmids, frequently carried by environmental and pathogenic bacteria, play a critical role in rapid dissemination of antibiotic resistance through conjugation. The use of antibiot-ics further induces this conjugative transmission between bacteria and thereby plays a role in the rise of antibiotic resistance. This highlights the need for a fundamental understanding of the regu-lation of transmission, to limit the problem. In addition, antibiotics induce the bacterial SOS re-sponse, however, whether using SOS as target can reduce conjugation, has been unclear. In this research, we used SOS-inducing compounds, SOS-mutants, conjugation and proteomics, and showed that antibiotic induced conjugation and induction of the SOS response happens through different mechanisms. This provides a new insight, which affects future strategies to control the spread of antibiotics.