FIG. 6.

The che operon mutant is impaired in, but not null for, chemotaxis. (A) Chemotaxis toward 10 mM malate, as determined by a soft agar plate assay. Both plates were inoculated with the same number of cells and incubated at 28°C for 48 h. (B) The average chemotactic-ring diameters are expressed as percentages relative to that of the 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 che operon mutant were found to be statistically significant with all chemoeffectors tested. (C) Reversal frequencies of free-swimming cells of the wild type and the che mutant on malate (filled bars) and fructose (open bars). The reversal swimming frequency was determined as described in Materials and Methods. Standard deviations to the means are indicated.