抄録
Many bacteria swim by rotating their helical flagellar filaments, which act as screw propellers. We measured relationship between flagellar shape and swimming speed of Vibrio alginolyticus cells by using laser dark field microscopy (LDM). The pitch was observed to slightly decrease when a cell swam forward, while it was observed to slightly increase when a cell swam backward. The radius seemed to have the same tendency to the pitch, though the change was rather small compared with the experimental error. The deformation in flagellar helix observed here was estimated to hardly influence the ratio of swimming speed to flagellar rotation rate (v-ƒ ratio) that corresponds to the propulsion efficiency by only a few percent.
