48. Photobacterium 



The light producing or luminescent bacteria do not form a 

 homogeneous group either physiologically or morphologically. To 

 group them together into one genus, Photobacterium, may not be 

 in the best interest of a sound taxonomy. Luminescence, however, 

 is such a striking phenomenon that one is apt to regard it as of 

 fundamental taxonomic importance even though it is not a particu- 

 larly stable characteristic. 



Five cultures of the group were received from H. Spencer of 

 the Humber Laboratory, England; namely Photobacterium sepiae, 

 P. albensis, P. harveiji, P. phosphoreum, and P. splendidum. P. 

 fischeri was received from M. J. Cormier, Oak Ridge, Tennessee. 

 P. phosphor escens, strains L-342 and L-1761, were received from 

 Kluyver's laboratory in Holland through R. S. Breed (see Fig. 

 51). All the cultures were halophilic and rather psychrophilic. 

 With 3% sodium chloride added to the proper medium and in- 

 cubated at 20° C, good growth was obtained. With the excep- 

 tion of P. sepiae, all produced some light in one medium or an- 

 other. 



Fig. 51. a. Photobacterium fischeri, Cormier. Polar multitrichous flagella. 

 The flagella are short with few curves, usually less than one complete wave, 

 and long wavelength. Resembles Spirillum. 



b. P. fischeri, Cormier. Same slide as in a. This picture shows the "micro- 

 cyst" form which is common in this strain. The flagellation is the same as in 

 the long, or normal, form. 



c. P. phosphor escens, Kluyver L-342. All individuals in this culture had a 

 spherical soma with a more or less well-defined capsule. Polar monotrichous 

 flagella. 



d and e. P. phosphoreum, Spencer. All individuals in this culture were 

 spherical with a single flagellum. In e is shown a dividing form with the 

 typical location of the flagellum, indicating polarity. 



f. P. albensis, Spencer. In addition to the curved rod illustrated, this 

 culture also showed straight rods and spiral forms. The straight and curved rods 

 showed polar monotrichous flagellation. The spiral forms occasionally had 

 tufts of polar flagella. 



g, h. P. splendidum, Spencer. Both spiral and spherical individuals were 

 present in this culture. In g is shown a slightly spiral form and in h, a spherical 

 form. The flagellation is polar monotrichous. 



i. P. sepiae, Spencer. Straight rods with polar monotrichous flagella. 

 j. P. harveiji, Spencer. Straight rods with single polar flagella. 



120 



