Myristic acid stimulation of bacterial bioluminescence in "aldehyde" mutants

The involvement of long chain aldehyde in bacterial luminescence was known both from its being required for light emission in the in vitro reaction with pure luciferase and from its ability to stimulate luminescence in vivo in a certain class of dark "aldehyde" mutants. We have found that the luminescence of some (but not all) of such aldehyde mutants is also stimulated by long chain aliphatic fatty acids, with a marked specificity for myristic (tetradecanoic) acid. This stimulation has been demonstrated in aldehyde mutants of two species of luminous bacteria, Beneckea harveyi and Photobacterium fischeri. The responses, both in intensity and yield, are proportional to the amount of added tetradecanoic acid over a 1000-fold range, down to 10 pmol ml-1. Unsaturated long chain fatty acids are potent inhibitors of the tetradecanoic acid stimulation, but they do not effect the in vivo luminescence of wild-type bacteria.