PSEUDOMONAS FLUORESGENS 511 



the fluid is turbid, yellowish-green, and sometimes granular ; there may be saccate 

 liquefaction around the filiform growth as well. 



Broth. — -2 days at 25° C. Abundant growth, with dense turbidity ; yellowish-green colour ; 

 thick white ring growth and thin surface pellicle ; slight powdery sediment, dis- 

 integrating on shaking. After 5 days there is an abundant, visco-floccular deposit, 

 only partly disintegrating. Mawkish odour, like trimethylamine. 



Blood Serum. — 7 days at 25° C. Good, confluent, slightly raised growth, of greenish- 

 yellow colour ; medium is slightly green ; medium is partly digested in 14 days. 



Potato. — 6 days at 25° C. Abimdant, slightly raised, confluent, greenish- brown growth 

 with moist, glistening, contoured surface. Potato coloured green. Later, both 

 the growth and the potato take on a brownish colour. 



Resistance. — Destroyed by 55° C. in 1 hour. 



Metabolic. — Aerobic ; no growth anaerobicaUy. Opt. temp. 30-37° C. ; limits 5-42° C. 

 Forms a green pigment soluble in cliloroform and m water, called pyocyanin ; 

 forms a greenish-yeUow fluorescent pigment, soluble in water but not in chloro- 

 form. Nutritional : grows well on ordinary media ; in synthetic media, both 

 phosphate and sulphate are essential for production of fluorescent pigment. 



Biochemical. — Acid, no gas, in glucose. Indole — ; a false reaction may be given by 

 Bohme's reagent, the acid of which tiu-ns pyocyanin red. M.R. — , V.P. — , 

 Nitrate reduction — . H-^S — . NH3 production +. Catalase +• M.B. reduced. 

 Starch diastase — . L.M. peptonization and decolorization complete in 5 days at 

 30° C, may be shght preliminary clot ; milk often turned green. Growth in 

 citrate. 



Pathogenicity. — Low pathogenicity to man, giving rise to diarrhoea and general infections 

 in infants, and to suppm'ation. Cause of " blue pus." Gives rise to fever and 

 local abscess after subcutaneous injection into rabbits. 



Ps. fluorescens. — This organism is found in water, hail (Belli 1902), sewage, 

 and has been isolated from lemonade (Thoni 1911). It is motile by one or more 

 polar flagella. Many authors consider it a variety of Ps. pyocyanea, which has 

 become adapted to a purely saprophytic existence (Tanner 1918, Ruzicka 1898). 

 The differential characters may be given as follows : 



Ps. pyocyanea. Ps. fluorescens. 



(1) Opt. temp. 37° C; grows at 42° C. Opt. temp. 25° C. ; no growth at 42° C. 



(2) Pyocyanin and fluorescent pigment Fluorescent pigment only formed. 



formed. 



(3) Liquefaction in gelatin stratiform and Liquefaction in gelatin not always present : 



saccate. when present stratiform only. 



(4) Pathogenic to rabbits and guinea-pigs. Non-pathogenic to rabbits and guinea-pigs. 



These difierences are by no means constant. Further, since varieties of Ps. 

 pyocyanea may occur that fail to produce pyocyanin, and since achromogenic 

 varieties of both organisms are not uncommon, differentiation of the two organisms 

 is often impossible. 



Jordan (1899) studied 58 strains of Ps. fluorescens from water. He found that 

 33 of them liquefied gelatin, and produced acid, clot, and peptonization in milk ; 

 25 did not liquefy gelatin, and produced alkali in milk without coagulation. The 

 variations in reaction that may occur can be judged from the fact that Tanner 

 divided 42 strains, which he studied, into no fewer than 27 different groups. 



Ps. fluorescens is generally non-pathogenic to animals, but it may give rise to 

 a local abscess in rabbits and guinea-pigs. On the other hand, it is stated to be 

 frequently pathogenic to plants, especially cultivated vegetables, such as carrots, 

 cauliflowers and tomatoes, in which it causes areas of moist necrosis (Griffon 1909). 



