Fig. 2.

The motility of a statorless B. subtilis mutant (ΔABΔPS) expressing B. subtilis motAB (BS-AB), B. subtilis motPS (BS-PS), or B. clausii motAB (BCl-AB). (A) Motility in a soft-agar plate assay. Fresh cells were inoculated into LB medium (22) (pH 7.0) soft agar and incubated at 37°C for 16 h. (B–D) Motility in liquid medium. BS-AB (B), BS-PS (C), and BCl-AB (D) cells were grown at 37°C in LB medium (pH 7.0), and the swimming speed was measured at various concentrations of sodium in 1/20 tryptone yeast extract (TY) medium (5) as described in Materials and Methods. The pH values of TY/20 medium used in each assay are designated by symbols as indicated.