422 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



brown growth on agar streak 

 cultures — on agar plates round 

 granular colonies. 



Potato — Very slow scanty growth. 



Milk — Is not coagulated. No 

 acid or gas is formed. 



Aerobe — Facultative anaerobe. 



Non-pathogenic. 



BACILLUS LACTIOUS (Kruse) ; B. 

 GUNTHBRI, B. LACTIS AOIDI 

 (Leichmann); B. ACIDI PARA- 

 LACTIOI (Kozai). 



Source and habitat — Isolated from sour 



milk. 

 Morphology — Short thick rods, pointed 

 at the ends ; i m long, o-6 y. thick ; 

 in pairs or chains. 

 Staining reaction — Stains by Gram's 



method. 

 Motility — Non-motile. 

 Biology : cultural characters (^includ- 

 ing biochemical features). 



Bouillon — Slight turbidity when 

 no sugar is present ; marked if 

 sugar present. 



Gelatine plates and tubes — 

 Punctiform colonies, -5 ^ in dia- 

 meter — if sugar present colonies 

 are larger — always delicate in 

 structure. Non-liquefying. In 

 stab- cultures the growth only occurs 

 in depth. 



Agar plates and tubes — Delicate 

 transparent growth on agar plates. 

 Potato — A scanty limited growth. 

 Milk- — Coagulated with strongly 

 acid reaction. From milk sugar 

 pure dextro-rotatory lactic acid is 

 produced. No gas. 

 Facultative anaerobe. 

 Non-pathogenic. 

 Leichmann describes eleven lactic 

 acid bacilli, each of which shows 

 some differences. Esten describes 

 a B. acidi lacti, No. I, which Conn 

 considers identical with above. 



BACILLUS LACTIS OF PLUQGB. 



A series of milk organisms described 

 by numbers. A short account of 

 each will be given as follows : — 



Bacillus lactis. No. 1 (Fliigge). — 

 Thick, short, actively motile bacilli 

 with terminal spores. Gelatine 

 cultures : colonies indentated. 

 Rapid liquefaction of gelatine and 

 also of blood serum. On agar and 

 potato greyish-white growth. In 

 bouillon a general turbidity with 

 flocculent deposit. Milk is rapidly 

 coagulated. A facultative anae- 

 robe ; highly poisonous (Fliigge). 



Bacillus lactis, No. 2 (Fliigge). — 

 Short, plump, actively motile 

 bacilli with medial spores. Gela- 

 tine cultures : rapid liquefaction, 

 slow liquefaction of blood serum. 

 On agar and potato a whitish, 

 wrinkled and strongly viscous 

 coating. Bouillon : the only 

 appearance is the fonnation of a 

 surface membrane. Milk : floccu- 

 lent coagulation with slow peptoni- 

 sation. Very widely distributed 1 

 in nature {c.f. B. niesentericus 

 vulgatus). 



Bacillus lactis. No. S (Fliigge). - 

 Short, fine, sporing bacilli. Slo\ 

 liquefaction of gelatine. On agar ; 

 delicate, and on potato a luxuriant 

 slimy cream-coloured growth^ 

 Gas development in lactose-agal 

 stab-cultures. In bouillon isolatec 

 flocons. Milk rapidly coagulates 

 with development of gas and lab-ij 

 smell. Slow peptonisation of mill 

 Spores are killed in i hour at 100°, 

 Highly poisonous (Fliigge). 



Bacillus lactis. No. 4 (Fliigge).— 

 Short, fine, actively motile bacilli. 

 Spore formation. Gelatine cul- 

 tures : colonies indentated. 

 Marked liquefaction both of 

 gelatine and blood serum. On 



