cholerae O1/O139, which showed temperature-independent motility between 20 and 42°C, as shown in Figure 1. The difference between C. jejuni and H. pylori motility is clear at 42°C, at which temperature C. jejuni is still motile, but H. pylori motility has declined (Fig. 1). The swimming speed at 37°C was the fastest for C. jejuni (>100 μm/s); the swimming speeds of H. pylori, V. cholerae O1 and V. cholerae O139 were 55.4 ± 6.6, 80.2 ± 8.6 and 75.6 ± 8.9 μm/s,

respectively. The swimming speed of C. jejuni at 42°C was faster than at 37°C (>100 μm/s; the resolution limit of the assay system employed AZD4547 in vivo did not allow precise assessment of speed). The motility of C. coli was very similar to that of C. jejuni (Fig. 1); the swimming speeds at 37 or 42°C were >100 μm/s. Next, correlations between bacterial shape and motility were examined

for C. jejuni. C. jejuni enteritis strains (n = 30) and ATCC33560 all took the form of spiral rods with polar flagella at each selleck kinase inhibitor pole and were highly motile, as shown in Figures 1 and 2a, d. Five of the C. jejuni GBS strains (n = 7) strains took the form of motile spiral rods (as shown in Figs. 1 and 2a, d), whereas one strain (KB3439; belonging to ST22) took the form of a straight rod with polar flagella at each pole (Fig. 2b, e). Interestingly, strain KB3439 was highly motile (Fig. 1), its swimming speed of >100 μm/s (at 37–42°C) being similar to that of a spiral rod, indicating that a spiral body shape is not essential for motility. As expected, the remaining strain (KB3449; belonging to ST4051), which took the form of a straight rod without

flagella (Fig. 2c, f), showed no motility, (Fig. 1). As shown in Figure 3, all C. jejuni strains have cup-like structures (marked by closed arrowheads) at both ends of the bacterial spiral body, irrespective of their bacterial shapes or the presence or absence of flagella. These polar cup-like structures are located inside (and adjacent to) the inner membrane and are 33.8 ± 6.0 nm thick (including the inner membrane) and 206.4 ± 25.5 nm in length (n = 62), as shown in Figure 3a (inset panels in the right and middle lower corner). The space (cytoplasm) within the cup-like structures is less dense than the cytoplasm of the spiral (or straight) bodies (Fig. 3). Motile bacteria have a polar hollow for a flagellum Galeterone (Fig. 3a, b; indicated by arrows), in contrast to non-motile bacteria (Fig. 3c). Negative staining of C. jejuni cells (Fig. 4a, b) further demonstrated that inner tubular structures extend from the inner membrane and open into a funnel shape on the bacterial cell surface (diameter at the bacterial cell surface, 80.8 ± 10.1 nm [n = 31]); flagella expanding into a funnel shape toward the environment. The inner tubular structure is incompletely shown in Figure 4b, probably due to incomplete penetration of uranyl acetate into the tubular structure from the bacterial surface (funnel shape) side. The funnel shape was also confirmed by thin sections of C.