The luminous bacterium of Leiognathus rivulatus was identified as Photobacterium fischeri. The bacterium assimilated such nitrogen sources as potassium nitrate, ammonium nitrate, ammonium sulfate, sodium nitrate, ammonium chloride, diammonium hydrogen phosphate and asparagin. Basal medium described by Farghaly was used. The bacterium assimilated such carbon sources as glucose, galactose, mannose, fructose, cellobiose, glycerin, calcium lactate and dextrin. The bacterium maintained luminescence about two months at 23℃ in 1 % yeast extract sea water medium. Intensity of bacterial luminescence in 1 % peptone-, hydrolized casein- and meat extract-media was greater than yeast extract medium during the first ten days, but thereafter the intensity of the former rapidly decreased. Duration of the bacterial luminescence is shown in Table 1. Table 2 shows the pH values of the media at which the luminescence disappeared. When glucose was used as carbon source, the luminescence disappeared after only one day in all cases. When the luminescence disappeared the pH values of the media were all below 5 in glucose and 6.1-6.7 in galactose. In order to adjust the pH value, 4 mg Ca-carbonate per ml of the medium was added before inoculation. The results are shown in Table 3. Table 4 shows the pH values of the media containing Ca-carbonate at which the luminescence disappeared. Duration of luninescence was prolonged in glucose, galactose and Ca-lactate media. Excepting the media containing glucose, pH values of the media were raised.
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