DESCRIPTION OF SPECIES 



393 



AROMA BACTERIUM (Weigmann). 



Source and habitat — Milk and its pro- 

 ducts. 



Morphology — Bacillus. Thick rods of 

 varying length, at times curved, 

 isolated, or in groups. 



Staining reaction — Ordinary aniline 

 stains. 



Spore formation — Present. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — Becomes cloudy after 

 24 hours ; a thin veil forms on the 

 surface of the medium ; later, the 

 medium clears with formation of 

 thick, surface veil ; no deposit. 



Gelatine — In stab-cultures a thin 

 beaded growth along the needle 

 track, with slow liquefaction of 

 gelatine in "stocking" form, the 

 growth forming a creamy deposit 

 as the liquefaction proceeds. In 

 stroke cultures a similar growth. 



Agar — Stab - cultures, sparse 

 growth along the needle track, 

 with hob-nail formation on surface, 

 of a creamy nature and yellowish 

 tint. On stroke cultures a creamy- 

 yellowish growth along- needle 

 track. On glycerine-agar, growth 

 more rapid and of similar nature 

 to above, but of a drier nature and 

 slightly wrinkled with age. 



Potato — At first a smooth, white 

 growth, darkening slightly with 

 age, and showing fine granulation. 

 Milk — No coagulation. Deposit 

 formed at bottom of tube. 

 Aerobic. 

 Non-pathogenic. 



BACILLUS ACIDI LACTICI 



(Hijppe). 



Source and habitat— Sour milk. 

 Morphology— 0\2\ rods ; o-6 to 2 m 



long, 0-4 to 0-6 M broad ; usually in 



pairs, rarely in chains. 



Staining reaction — Ordinary stains 

 and slightly by Gram's method. 



Motility — No flagella ; non-motile. 

 Spore formation — Absent. 

 Biology : cultural characters {includ- 

 ing biochemical features') — Good 

 growth at room temperature and 

 blood heat. 



Bouillon — Diffuse turbidity ; 

 abundant sediment. 



Gelatine plates and tubes — Colo- 

 nies similar to B. colt; small, 

 smooth, round, white. 



Agar plates and tubes— Colonies 

 similar to B. coli j small, smooth, 

 white growths, moist and shiny. 



Potato — A wavy, smooth-edged 

 growth, elevated ; greyish- white or 

 yellowish - white in colour, some- 

 times turning brown. 



Milk — Solid coagulation, leaving 

 clear fluid ; occasionally some gas 

 bubbles. Lactic and acetic acids 

 are produced. Powers of acid 

 coagulation of milk are gradually 

 lost after long cultivation upon 

 gelatine or agar. 



Anaerobic or aerobic — Grows well 

 aerobically, and if sugar present in 

 medium anaerobically also. 



Non-pathogenic. 



BACILLUS ACTINOBACTER 



(Duclaux). 



Source and habitat — Widespread in 

 nature and common in milk, the 

 most favourable medium for its 

 growth. 



Bacillus — In milk, fine rods from 2 

 to 3 M long. Isolated or united in 

 pairs. 



Capsule J motility — In milk the organ- 

 ism, either singly or in pairs, end- 

 on-end, is surrounded with an 

 ovoid or rounded gelatinous cap- 

 sule of 5 to 6 M broad. The organ- 

 ism is non-motile. 



Spore formation —None observed. 



