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Variations in the intensity of luminescence of Photobacterium belozerskii grown on different media were studied. In the course of growth the luminescence intensity changed by 2 to 4 orders of magnitude, depending on the nutrient medium used. Exogenous myristic aldehyde added to the bacterial suspension at the time of luminescence measurement decreased the intensity to a degree, which was essentially independent from the initial level. The onset of an increase in the luminescence intensity depended on the nutrient medium. An addition of arginine, proline or asparagine to the medium reduced the latent period and simultaneously increased the luminescent intensity by 30, 10 and 5-10 times, respectively. Arginine and proline added to the minimal medium at the time of an increase in the luminescence of P. belozerskii enhanced the rate of biosynthesis of the luminescent system enzymes by 32 and 10 times, respectively. In response to a combined action of these amino acis, the rate of luciferase biosynthesis grew by 630 times. Possible mechanisms and factors responsible for the above changes are discussed.

The effect of cAMP on the parameters characterizing the development of luminescence in Photobacterium belozerskii is discussed. An addition of cAMP to the culture medium shortened the latent time of luminescence development by 3--6 hours. The intensity of bacterial luminescence increased with a varying rate. During luminescence enhancement the rate of luciferase synthesis increased by a factor of 10 to 10(3). The rate of luciferase synthesis and the maxiumum level of bacterial luminescence when cultivated in the glycerol medium containing arginine and proline increased under the influence of cAMP by 100 and 40 times, respectively. After an addition to cAMP into the glucose medium these parameters of luminescence development increased only when the medium contained arginine. After an addition of cAMP into the glycerol medium the rate of bacterial growth increased two-fold. Possible mechanisms regulating luminescence development and cAMP involvement in these processes are discussed.