3.1.1 Extracellular appendages
Henrichsen [37] studied the movement behavior of 40 kinds of bacteria on the surface, and summed up 6 movement modes: swimming, swarming, gliding, twitching, sliding and Darting. Bacterial motility is related to the bacteria’s motility organ, the flagellum, the bacteriophage, which resembles a kind of spiral propeller that, by rotating itself, gives the cell the ability to move[38-39]. For example, swimming is mainly due to the rotation of the flagellum [40], surging relies on flagella and extracellular secretions [41], and rubbing comes from the release and contraction of the bacteriophage[42]. In the initial stages of bacterial attachment to the interface, flagellar motility facilitates the interaction of the bacteria with the interface, and flagellar filaments can adhere directly to the interface substrate[27].