Efficient plasmid transfer via natural competence in a synthetic microbial community

Abstract

The molecular and ecological factors shaping horizontal gene transfer (HGT) via natural transformation in microbial communities are largely unknown, which is critical for understanding the emergence of antibiotic-resistant pathogens. We investigate key factors shaping HGT in a microbial community by quantifying extracellular DNA release, species growth and HGT efficiency over time. In the community, plasmid release and HGT efficiency are significantly enhanced than the respective monocultures. The donor is a key determinant of HGT efficiency as plasmids induce the SOS response, enter a multimerized state, and are released at high concentrations, yielding efficient HGT. HGT is independent of the donor viability state as live and dead donor cells transfer the plasmid with high efficiency and is only reduced in response to high donor lysis rates. In sum, plasmid HGT via natural competence depends on an interplay of plasmid properties, donor stress responses and lysis rates and inter-species interactions.