Type IV pili (TFP), the filament-like surface appendages found in many bacteria species, have been known to facilitate initial attachments of planktonic cells to surfaces, and next acted as linear actuators to mediate twitching motility that plays significant roles developing of biofilms. We have performed a series of studies following fundamental questions - Can bacteria deploy their TFP to control their twitching motilities, thus facilitating themselves to adapt to the microenvironments? If yes, how do they achieve it? If knowing the underlying mechanisms, can we control the bacterial motilities on the surface? If yes, Can we control biofilm formation by controlling their motilities?
In our studies, we combined distinctive state-of-the-art techniques to address those specific fundamental questions. There are two examples that we have done:
Figure Captions: Analysis of the velocity prolife of ∆filM mutant on a variety of surfaces. (A) Typical trajectory of leading and trailing pole in a crawling ∆filM cell, yellow and pink symbols show raw data, cyan and red lines indicate the denoised data. Typical velocity amplitude of leading pole in a crawling ∆filM cell on (B) glass surface at 30℃, (C) glass surface at 37℃, (D) short-brush surface at 30℃, (E) short-brush surface at 37 ℃, (F) long-brush surface at 30℃, (G) long-brush surface at 37 ℃.
In this example, we fabricated a surface that was grafted with a layer of thermally sensitive polymer chains, like a brush, thus its softness is easily adjusted by a small temperature change (30-37°C), which enables us to validate the possible mechanical responding of the TFP-driven crawling motility in Pseudomonas aeruginosa. We explicitly demonstrate that P. aeruginosa cells can use TFP to generate much more slingshot motions over crawling on viscous shear-thinning surfaces. Our results indicate that such responding leads to an advantageous exploring or colonizing for cells on surfaces in which energy dissipation reduces up to ~90% over crawling.