Adverse conditions which cause lack of flagella in Escherichia coli.

Wild-type Escherichia coli was not motile when grown in tryptone broth under the following adverse conditions: the presence of high temperature [J. Adler and B. Templeton, J. Gen. Microbiol. 46:175-184, 1967; R. B. Morrison and J. McCapra, Nature (London) 192:774-776, 1961; K. Ogiuti, Jpn. J. Exp. Med. 14:19-28, 1936], high concentrations of salts, high concentrations of carbohydrates, high concentrations of low-molecular-weight alcohols, or the pressure of gyrase inhibitors. Under all these conditions, growth was necessary for the loss of motility. This loss of motility was correlated with a reduction in the amount of cellular flagellin. We isolated and studied mutants that are resistant to suppression of motility by some of these conditions, because of the ability to synthesize flagella under these conditions. The mutations were mapped to 42 min, a region of the chromosome where many of the flagellar genes map. We also studied the effect of a preexisting gyrA mutation which allowed flagellar formation in the presence of nalidixate.