A Bacterium's Sense of “Touch”

The sheer number of bacteria living on solid surfaces makes a compelling argument for the existence of surface sensing mechanisms. However, surface sensing abilities have not been widely studied in bacteria, because such abilities are not macroscopically observable in attached organisms with limited mobility. We report experimental evidence that attached Staphylococcus aureus cells recognize the steep gradient near their substrate interface and localize substrate-specific biomolecules toward that region. We present Atomic Force Microscopy-based affinity maps which reflect the cells' biochemical sensory response to the substrate and provide a unique view of regions indicating specific binding activity and bond resilience.