New prodigiosin-like pigment from Alteromonas rubra.

The red prodigiosin-like pigment from Alteromonas rubra was shown to be a mixture of prodigiosin (pigment 1) and a new cyclic isomer (pigment 2). The new structure was elucidated by mass and nuclear magnetic resonance spectra. Careful examinations of the prodigiosins produced by Serratia marcescens, Vibrio psychoerythrus, and an unidentified red bacterium (LL-100-6) failed to disclose any of the new pigment, pigment 2.