Fig. 2

Bacterial movement and the microenvironment of the zebrafish larval intestine. a Swimming speeds of the bacteria in the three segments. The control indicates bacteria in culture fluid on a glass slide. Solid symbols and error bars indicate the mean and standard deviation, respectively (N = 6 fish). p values are determined by the Mann–Whitney–Wilcoxon test. b Diffusion coefficients of fluorescent tracer particles in the three segments. All data points are gray. The inset indicates the ratio of the diffusion coefficients in the three segments to the control. c Bacterial orientation φ was defined as the angle from the centerline vector s of the intestine. d–f Probability density distribution of the bacterial orientation in the three segments after cell distribution reached a steady state: d anterior intestine, e middle intestine, and f posterior intestine