4i6 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



is irregular, certain elements hold- 

 ing the stain. 



Motility — Motile. 



Spore formation — No sporulation ob- 

 served. 



Biology : cuUural characters {includ- 

 ing biochemical features) — Develop- 

 ment and fluorescence takes place 

 as low as 14° C, optimum tem- 

 perature for production of pig- 

 ment from 20° C. to 22° C, for 

 growth, 28° C. At 32° C. there 

 is no fluorescence; growth will take 

 place up to 42° C. but without 

 fluorescence. 



Bouillon — Medium becomes 

 turbid after 12 hours ; no surface 

 veil, or if any, very slight. Heavy 

 precipitate at bottom of the tube. 

 Fluorescence in 24 to 48 hours ; 

 the liquid becomes yellow by 

 transmitted light, light green by 

 reflected light — and remains 

 turbid for lengthened period. 

 When it clears, in very old cul- 

 tures, the green fluorescence has 

 diminished and the bouillon 

 assumes a slightly brownish tint. 



Gelatine plates and tubes — The 

 gelatine is rapidly liquefied, the 

 liquid assuming a green tint in the 

 upper portion. When liquefaction 

 has reached to the bottom of the 

 tube a thick whitish sediment is 

 deposited, the green tint of the 

 liquid disappears or is replaced by 

 a brownish coloration. 



Agar — A thick mucous surface 

 growth, viscous and of a greyish- 

 yellow colour. The medium is often 

 coloured green in its upper portion. 



Potato — A thin glistening growth 

 of a dirty yellow colour. 



Milk — Slow viscous coagulation 

 with tardy fluorescence. The liquid 

 is alkaline. 



Aerobic. 



Non-pathogenic. 



BAOILIiUS PliUOBESOEJNS NON- 

 lilQUBFACIBNS. 



{^B. fluorescens putriaus, Fliigge). 



Source and habitat — Air and water ; 

 thence to milk. 



Morphology J form and dimensions — 

 Motile rods -4 /t broad by 2 to 2-2 fi. 

 long. 



Biology : cultural characters {includ- 

 ing biochemical features). 



Bouillon — The liquid becomes soon 

 turbid at 20° C. ; in 3 or 4 

 days formation of a fragile veil, 

 easily torn ; abundant whitish 

 precipitate at bottom of tube. The 

 liquid presents a general fluor- 

 escence, but much less pronounced 

 than in the case of B. fluoresce7ts 

 liquefaciens. 



Gelatine plates — In plate cultures 

 colonies appear as small trans- 

 parent slightly yellowish discs. 

 Those which reach the surface 

 develop quickly and in a few days 

 appear as hyaline pellicles with 

 sinuous borders and irregular 

 surface, resembling slightly the 

 colonies of B. typhosus, but flatter 

 and much larger. The surround- 

 ing medium assumes a green tint 

 and the plate gives off a strong 

 urine-like odour. 



Agar — A greyish mucous - like 

 growth ; the medium assumes a 

 greenish tint. 



Potato. — Cultures somewhat re- 

 semble that of B. typhosus in its 

 early stages. 



Almost all cultures, but especi- 

 ally those upon potato or in bouillon 

 develop an odour, at times very 

 strong, resembling that of putrified 

 urine. At times, however, those 

 upon gelatine and agar may be 

 almost odourless. 



Aerobic. 



Non-pathogenic. 



