29. Chromobacteriutn 



The genus Chromohacterium has two characteristics b\' which 

 it may be identified and differentiated from all other bacterial 

 genera: the water insoluble purple pigment and the mixed polar 

 and peritrichous flagellation. Physiologically the genus is hetero- 

 geneous, including psychrophiles and mesophiles, carbohydrate 

 fermenters and nonfermenters. Opinions differ regarding the tax- 

 onomy of the genus but the author recognizes three species: 

 Chromohacterium viokiceum, Chromohacterium manilue, and 

 Chromohacterium laurentium (Fig. 31). Twenty-eight selected 

 cultures were studied, including several strains of each species. 



Flagellar Characteristics 



A polar, predominantly single, flagellum could be demonstrated 

 in all strains. With some strains, particularly of C. manilae, the 

 polar flagellum could not be stained with the standard flagella 

 stain. Fairly satisfactory staining was obtained by the modified 

 flagella stain with double the normal concentration of tannic acid. 

 In addition to the polar flagellum, all but four strains showed a 

 variable number of lateral flagella. The lateral flagella always 

 stained readily with the standard stain. They diflered from the 

 polar flagella by having a much shorter wavelength. By plating 

 the cultures in semisolid agar and fishing from the periphery of 

 the most spreading colonies, the number of lateral flagella could 

 be increased. The four strains which showed only polar flagella, 

 however, did not show lateral flagella by this technique. The 

 wavelength and amphtude of ten polar and of ten lateral flagella 

 on as many individuals were measured. In Table V are recorded 

 the mean values of these measurements. 



Fig. 31. a, b, c, d, e. Chromohacterium manilae. Note the weakly stained 

 polar flagellum, compared to the lateral flagella, in b, c and d. These polar 

 flagella did not stain with the usual stain formula. 



f. C. violaceum. A polar and a lateral flagellum of different wavelength. 



g. C. laurentium. Mixed polar and peritrichous flagellation, 

 a-g. From E. Lcifson, /. Bacteriol. 71, 393-400 ( 1956). 



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