Behavioral mutants of Rhizobium meliloti.

Rhizobium meliloti exhibited behavior resembling that of other chemotactic bacteria. Nonflagellated, nonmotile but flagellated, and nonchemotactic mutants were isolated, and genetic mapping placed all three types of lesions within a small region of the R. Meliloti chromosome. Results from nodulation experiments performed with these mutants indicate that members of the three classes (Fla-, Mot-, and Che-) infect and produce as many nodules on alfalfa plants as does the wild-type strain.