Increasing prevalence of (multi)drug resistant bacterial pathogens has become one of the most pressing public health threats. A number of clinically important drug-resistant pathogens have acquired antimicrobial resistance genes (AMRg) from non-pathogenic commensal or environmental microbial AMRg reservoirs through horizontal gene transfer (HGT). HGT is importantly contributing also to dissemination of their virulence factors in microbial communities. Nevertheless, mechanisms and dynamics of horizontal gene transfer among bacteria are currently hindered by methods that typically rely on labeling and genetic modification of model strains. This enables the studies of HGT among wild type pathogenic and commensal strains in microbiomes. To overcome this challenge, we propose to develop a sensitive electronic chip based on two-dimensional (2D) material channels with mechanical strain-dependent properties for real-time label-free direct quantification of conjugative interactions. We will use E. coli as a model system and immobilize populations of donor and recipient cells on specifically designed array-formatted chips to allow for mapping of conjugation in situ. Upon conjugative interaction, the pili extension, contact with recipient cell and retraction/rotation cause shear force that are expected to substantially modulate electronic properties of the 2D material channel and result in a measurable change in electrical signal. Graphene will be used as a proof-of- concept 2D material. The continuous probing of the electrical resistance is expected to provide quantitative information on the dynamics and rate of conjugative interactions among bacteria immobilized in a chip. Ultrathin and transparent nature of 2D materials will enable concurrent validation of conjugative interactions by confocal laser scanning microscopy of fluorescently labeled cells and pili in real-time.
Microbial conjugation is one of the main contributors to rapid antimicrobial resistance and virulence gene dissemination. Currently established methods are hindering investigations of rates and mechanisms of inter- and intraspecies conjugation, as they rely on cell labeling and genetic modification of laboratory strains. To overcome this challenge, we propose to develop a graphene-based chip for label-free quantitative spatially detection of microbial conjugative interactions through changes in the resistivity of a 2D material.
