Characterization of a fish symbiont of Photobacterium phosphoreum with altered spectral properties (abstract of paper presented at 14th International Symposium on Bioluminescence and Chemiluminescence)

Bacteria cultured from the photophore of a Physiculus spp. fish recovered from the Arabian Sea produced a distinctive blue luminescence that was brighter than other isolates on laboratory culture. Morphological characterization and biochemical profiling suggested that this bacterium belonged to the species Photobacterium phosphoreum, and 16S sequence analysis con- firmed that this isolate was closely related to this species. Analysis of luxA identified only small differences in the gene sequence, but the two organisms had different autoinducer profiles. Spectral analysis confirmed that the luminescence had a different λmax value to that of P. phosphoreum and a novel lumP (lumazine) gene was identified. This would account for the different spectral properties and suggests that this bacterium represents a new subspecies of P. phosphoreum.