Isolation, identification, and several characteristics of luminous bacteria.

In order to apply bioluminescence of luminous bacteria to industrial use, isolation of luminous bacteria from various sources was carried out on the basis of strong light intensity, and 18 strains were obtained. Eleven of these strains were identified as Photobacterium phosphoreum and seven as Vibrio fischeri.Maximum light intensities of these isolates were quite different among strains tested and two stock cultures of luminous bacteria supplied by the American Type Culture Collection had a very poor bioluminescence compared to the new isolates. Bioluminescent emission spectra from the two isolated strains were fairly different from each other, indicating the possibility of obtaining luminous bacteria which could emit light of different colors.While cultivation of some luminous bacteria was repeated several times in a liquid medium, decrease of light intensity was observed. By spreading the culture broth on an agar plate medium, three kinds of colonies were observed. They were quite different in the appearance of colonies and maximum light intensity. These results suggest that the occurrence of dim mutants in liquid cultures is disadvantageous for maintaining the light intensity constant and a strain which could be as stable as possible at this point should be used for industrial purpose.