Programmed Death of Injured Pseudomonas aeruginosa on Mechano-Bactericidal Surfaces.

Mechano-bactericidal surfaces deliver lethal effects to contacting bacteria. Until now, cell death has been attributed to the mechanical stress imparted to the bacterial cell envelope by the surface nanostructures; however, the process of bacterial death encountering nanostructured surfaces has not been fully illuminated. Here, we perform an in-depth investigation of the mechano-bactericidal action of black silicon (bSi) surfaces toward Gram-negative bacteria Pseudomonas aeruginosa . We discover that the mechanical injury is not sufficient to kill the bacteria immediately due to the survival of the inner plasma membrane. Instead, such sublethal mechanical injury leads to apoptosis-like death (ALD) in affected bacteria. In addition, when the mechanical stress is removed, the self-accumulated reactive oxygen species (ROS) incur poststress ALD in damaged cells in a nonstressed environment, revealing that the mechano-bactericidal actions have sustained physiological effects on the bacterium. This work creates a new facet and can introduce many new regulation tools to this field.