(229b) Conjugation in Escherichia coli biofilms on Poly(dimethylsiloxane) Surfaces with Microtopographic Patterns

Bacterial biofilms are less susceptible to antimicrobials and play an important role in the spread of antibiotic resistance due to close cell-to-cell contact. As an important surface character, topography has been shown to affect bacterial-surface interactions and biofilm formation. To understand if surface topography can also affect horizontal gene transfer in biofilms, we prepared poly(dimenthylsiloxane) (PDMS) surfaces with 20 μm by 20 μm, 50 μm by 50 μm, and 100 μm by 100 μm protruding square-shaped patterns (all features are 10 µm tall). Biofilm formation and associated conjugation on these surfaces were studied using fluorescently labeled donor and recipient strains of Escherichia coli. The results demonstrated that surface topography with an inter-pattern distance larger than 10 µm can promote biofilm formation with the majority of cells attached on the side of protruding features. This location was also found to be a â??hot spotâ? for biofilm-associated conjugation due to the increase in cell density. Furthermore, a motility (motB) mutant of E. coli exhibited defects in biofilm formation and conjugation, which was recovered by complementing the motB gene on a plasmid. These results suggest that bacterial motility is important for biofilm-associated conjugation, and optimizing surface topography is a potential strategy for the design of antifouling materials.