A luminous bacterium that emits yellow light.

A strain of Photobacterium fischeri that emits yellow light has been isolated from seawater. The bimodal spectrum, which is unique among the luminous bacteria, consists of a major band with a maximum at 545 nanometers and a minor band with a maximum at 500 nanometers. The former represents a heretofore unreported range of emission for luminous bacteria, while the latter coincides with the emission spectrum of typical blue-greeen-emitting strains of P. fischeri. The relative contributions of these two bands to the total in vivo luminescence changes as a function of ambient temperature. When luciferase is extracted and luminescence observed in vitro, the emission is entirely blue-green, identical with that of luciferase isolated from other strains of P. fischeri.