Induction of nonpigmented variants of Erwinia herbicola by incubation at supraoptimal temperatures.

Several strains of Erwinia herbicola produce white variants at high frequency when grown in yeast beef broth at 37 C. The relationships of the variants of E. herbicola Y46 to the parent strain have been studied with respect to cultural, morphological, physiological and serological features. All the white variants are auxotrophic, showing a requirement for thiamine, and no instance of reversion was observed. Representative variants show reactions similar to the parent strain on treatment with both virulent and temperate phages. Possible mechanisms by which the variants could arise are indicated.