396 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



from cream ripened with this 

 organism has an unpleasant flavour 

 and aroma. 



Aerobic. 



Non-pathogenic. 



BACILLUS ARBORESOBNS LACTIS, 

 No. 2 (Conn). 



Source and habitat — Milk. 



Morphology — 8 /x by 4 /u ; occasionally 

 two or three rods together, but no 

 chains. 



Staining reaction — Ordinary aniline 

 stains. 



Spore formation— Spores at one end 

 of bacillus (tetanus type) ; size of 

 spores I M by 1-2 m. 



Biology : cultural characters {includ- 

 ing biochemical features) — In 

 bouillon a tough pellicle is formed 

 which sinks if disturbed and forms 

 a flocculent sediment. 



Gelatine plates and tubes — Colo- 

 nies show radiating fibres strewn 

 with knots ; fibres fine and branch- 

 ing, growing mostly under surface. 

 In stab-cultures an arborescent 

 growth occurs ; fibres ending in 

 knots. Liquefaction ; dense, cloudy 

 liquid. 



Agar plates and tubes — Thin ; 

 hardly visible growth. 



Potato — Thin and scanty growth. 



Milk — No effect produced in 

 milk. 



Non-pathogenic. 



BACILLUS ANANA (Conn). 

 Source and habitat — Milk, 

 Morphology— -5 /* broad, i to i-2 /a long. 

 Staining reaction — Ordinary aniline 



stains. 

 Biology : cultural characters {includ- 

 ing biochemical features). 



Gelatine plates and tubes — Round 

 opaque granular colonies breaking 



up to form a pit covered with 

 mottled granular masses. Lique- 

 faction. In stab-cultures a narrow 

 pit is produced containing a 

 granular liquid. The pit broadens 

 at the surface and contains very 

 cloudy liquid. 



Agar plates and tubes — A moist 

 white abundant growth. 



Potato — A very thick, white, 

 abundant growth, having the odour 

 of pine-apple. 



Milk — Curdles at 20° C. into a 

 soft curd. No digestion noticeable. 

 No curdling at 36° C. 



Aerobic. 



Non-pathogenic. 



BACILLUS AURANTIACUS. 



Source and habitat — From deep well 

 water obtained from the chalk ; 

 thence to milk. 



Morphology — Short thick bacilli ; 1-7 

 fx, long by 0-6 m broad. Singly, in 

 pairs, or in threads. 



Staining reaction — Ordinary aniline 

 dyes. 



Motility — Present. 



Spore formation — None. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — Remains clear ; 

 growth occurs as a slight orange 

 deposit. There is a thin pellicle 

 exhibiting here and there bright 

 orange spots. 



Gelatine plates — There slowly 

 appears a bright orange puncti- 

 form growth, and there is no lique- 

 faction. 



Agar tubes — The growth shows 

 itself along the track of the needle. 

 It is a bright orange colour. 



Potato — Thick growth of a 

 brilliant orange-red colour. 



Aerobic. 



Non-pathogenic. 



