CHROMOBACTERIUM INDIGVM 637 



Chromobacterium indicum 



Isolation. — By Koch from the stomach of an ape. 



Morphology.— Slender, often curved, bacillus, 2-4 n long by 0-6 [x broad ; ^motile by peri- 



trichate flagella. Gram-negative. Non-acid-fast. 

 Cultural Characters. — Grows readily on ordinary media. 



Agar plate. — 2 days at 25° C. Colonies are circular, 1 mm. in diameter, amor- 

 phous, low convex, translucent, and pink, with a smooth surface and entire edge ; 

 butyrous in consistency and easily emulsifiable. After 5 days, there is usually a 

 thin, transparent, colourless peripheral fringe with a finely lobate edge. 



Oelatin. — 5 days at 20° C. Abundant growth ; complete hquefaction of gelatin ; 

 upper I cm. of the liquefied gelatin is densely turbid and bright red in colour ; 

 pinkish deposit at bottom of tube. 



Broth. — 2 days, 25° G. Luxuriant growth, with dense turbidity, a pink surface 

 pellicle and ring growth, and an abundant, moderately granular, pink deposit, 

 which disintegrates partly on shaking. 



Potato. — 6 days, 25° C. Moderate, slightly raised, confluent growth of cafe-au- 

 lait colour, having a smooth or finely granular, contoured, moist, glistening surface. 

 Loeffler's serum. — 5 days, 25° C. Abundant, confluent, raised, pinkish growth, 

 with a glistening contoured surface ; slight digestion, increasing with further 

 incubation. 

 Biochemical Reactions. — Same as Chr. prodigiosum. 

 Pathogenicity. — Nil. 



Chromobacterium kielense. — This organism, which was isolated from water, resembles 

 Chr. prodigiosum very closely ; it is not clear, in fact, that it is a separate species. It 

 is said uniformly to produce both acid and gas in carbohydrate media ; but as many 

 strains of Chr. prodigiosum also produce gas, this distinction is an imperfect one. 



Group Forming a Yellow or Orange Pigment.- — Chr. aquatile, an organism 

 isolated by the Franklands (1889) from deep wells in the Kent chalk, is a typical 

 example of this group. The yellow pigment is insoluble in water but dissolves 

 in alcohol, ether and chloroform. In non-albuminous media it is developed slowly ; 

 but it appears rapidly in a peptone solution containing magnesium sulphate and 

 dipotassium hydrogen phosphate. 



We append a detailed description of Chr. aquatile and Chr. typhi-flavum, together 

 with brief notes on a few of the other members of this group. The identity of Chr. 

 aquatile is not very certain, since the original description was incomplete. The 

 present description is founded on a study of the strain of Chr. aquatile obtained from 

 the National Collection of Type Cultures, London. Chr. typhi-flavum is the name 

 we suggest for the organism commonly known as Bad. typhi flavum. Though 

 suspected by certain German workers of being a pigmented variant of the true 

 typhoid bacillus, the evidence, which has been critically reviewed by Cruickshank 

 (1935), is quite insufficient to establish any such relationship. 



Chromobacterium aquatile 



Synonym. — Bacillus aquatilis Frankland. 



Hah itat. — Water. 



Morphology. — Slender rod-shaped organism, 2*5 /z X 0*6 /x ; axis straight, sides parallel, 

 ends rounded ; arranged in bundles ; length irregular. Motile by peritrichate 

 flagella. Non-sporing ; non-oapsulated. Gram-negative ; non-acid-fast. 



