Bacteria Can Rotate while Body-Tethered to a Solid Surface.

The attachment of bacteria to solid surfaces has been studied primarily through the modes of pili or flagella tethering. We report on a common feature of tethering in pililess strains of three species of monotrichous bacteria-(Vibrio alginolyticus, Pseudomonas aeruginosa, and Caulobacter crescentus)-namely, that they may become tethered to the surface by their cell body rather than by their flagellum. These tethered bacteria rotate in alternating directions about a pivot point located under the cell body. Using high-intensity darkfield microscopy, we observed that, in most cases, the flagellum of a tethered Vibrio alginolyticus rotates together with the cell body. We name this distinct mode of attachment body tethering. Observing hundreds of rotating bacteria tethered to the surface, we find that body tethering is a more common mode of attachment than flagellum tethering for these three strains of bacteria. Our results confirm that body tethering is a key mechanism for the surface attachment of bacteria without pili. Recognizing body tethering as a robust mode of bacterial attachment to surfaces may have broad implications in the study of bacterial adhesion and biofilm formation.