ATP pool and bioluminescence in psychrophilic bacteria Photobacterium phosphoreum

Bioluminescence activity and ATP pool were investigated in the cells of psychrophilic bacteria Photobacterium phosphoreum collected from the exponential and stationary growth phases and immobilized in polyvinyl alcohol (PVA) cryogel. In liquid culture, ATP pool remained at an almost constant level throughout the luminescence cycle (over 100 h). The ATP pool in the stationary-phase and PVA-immobilized cells remained constant throughout their incubation in the medium (over 200 h) and in 3% NaCl solution (over 100 h). Quantitative assessment of integral photon yield and ATP pool indicated that bioluminescence decay in growing or stationary cells was not caused by limitation from the energy substrates of the luciferase reaction. Kinetic and quantitative parameters of emission activity and ATP pool excluded the possibility of formation of the aldehyde substrate for luciferase via reduction of the relevant fatty acids in NADPH and ATP-dependent reductase reaction and its oxidation in the monooxygenase reaction. Our results indicate that the aliphatic aldehyde is not utilized in the process of light emission.