FIG. 1.

cheBR, cheB, and cheR mutants are deficient in chemotaxis. Chemotaxis of the A. brasilense wild-type strain (Sp7) and that of the mutants were compared by soft agar plate assay. Chemotactic-ring diameters were measured after incubation at 28°C for 48 h. (A) Representative soft agar plates with 10 mM malate as the sole carbon source. (B) The average chemotactic-ring diameters are expressed as percentages relative to that the of wild-type strain (defined as 100%). Error bars represent standard deviations from the means, calculated from at least three repetitions. Differences in the chemotactic-ring diameters of the wild type and the mutants were found to be statistically significant with all chemoeffectors tested.