Vibrio harveyi bioluminescence plays a role in stimulation of DNA repair

Although the genetics and biochemistry of bacterial luminescence have been investigated extensively, the biological role of this phenomenon remains un clear, Here it is shown that luxA, luxB and luxD mutants (unable to emit li ght) of the marine bacterium Vibrio harveyi are significantly more sensitiv e to UV irradiation when cultivated in the dark after irradiation than when cultivated under a white fluorescent lamp, This difference was much less p ronounced in the wild-type (luminescent) V. harveyi strain, survival of UV- irradiated Escherichia coli wild-type cells depended on subsequent cultivat ion conditions (in the dark or in the presence of external light), However, after UV irradiation, the percentage of surviving E. coli cells that bear V. harveyi genes responsible for luminescence was significantly higher than that of nonluminescent E, coli, irrespective of the subsequent cultivation conditions, Moreover, it is demonstrated that luminescence of V, harveyi c an be stimulated by UV irradiation even in diluted cultures, under conditio ns when light emission by these bacteria is normally impaired due to quorum sensing regulation, It is proposed that luminescent bacteria have an inter nal source of light which could be used in DNA repair by a photoreactivatio n process, Therefore, production of internal light ensuring effective DNA r epair seems to be at least one of the biological functions of bacterial lum inescence.