Plasmid-borne determinants of pigmentation and thiamine prototrophy in Erwinia herbicola

Strains of Erwinia herbicola lost yellow pigmentation and thiamine prototrophy at high frequency when grown at elevated temperature (38 degrees C) or in the presence of sodium dodecyl sulfate. All pigmentless, thiamine-auxotrophic variants had lost a large plasmid (ca. 350 megadaltons). Conversely, all pigmented, thiamine-prototrophic strains contained the large plasmid. The evidence presented indicates that pigmentation and thiamine prototrophy are specified or controlled by genes carried on the 350-megadalton plasmid.