Characteristics of the yellow pigment from a strain of Yersinia enterocolitica biovar 1.

Yersinia enterocolitica 195A14J, a milk-isolated strain of biovar 1, produces a non-diffusible yellow pigment and forms star-shaped colonies when grown on egg-yolk agar at 28 degrees C. Solubility properties and in situ Raman spectrum of the pigment support evidence that it is not a carotenoid, although it contains a 9 (+/- 1) double-bond polyenic chain. Pigmentless variants, also star-shaped, appeared with a frequency of ca.10(-3) when bacteria were grown at 38 degrees C. Agarose gel electrophoresis of DNA extracted from the pigmented strain revealed the presence of a 42-kb plasmid which was lost in pigmentless variants.