Bioluminescence-mediated stimulation of photoreactivation in bacteria

Although biochemistry and genetics of light emission by cells have been investigated in detail, a biological role for bacterial luminescence has remained obscure for a long time. It was proposed recently that luminescence may stimulate DNA repair, but the specific mechanism of this phenomenon was not investigated. Moreover, experiments showing decreased survival of UV-irradiated lux mutants relative to luminescent cells were performed previously using only one bacterial species, Vibrio harveyi. Here, we demonstrate that dark mutants of various strains of naturally luminescent bacteria (Photobacterium leiognathi, Photobacterium phosphoreum and Vibrio fischeri) are more sensitive to UV irradiation than wild-type cells. Thus, this phenomenon occurs not only in V. harveyi but also in other bacterial species. Using an artificial system of luminescent Escherichia coli in combination with phr mutants (defective in photolyase functions), we found that bacterial luminescence may stimulate photoreactivation, perhaps by providing photons that are necessary for photolyase activity.