ANTIBIOTICS 177 



iiud |)ul)i'iuluiii<- a<;i(I, ( ^sH^O^,. TJic furnici- is a colcjiiilcss, 

 crystalline, dibasic acid of m.p. 316 to 31 8 (J., whilst 

 puberulonic acid is a bright yellow, crystalline substance 

 having m.j). 298°C., which is thought to be the quinonoid 

 form of the quinol, puberulic acid. Puberulic acid 

 inhibits Gram -positive organisms at dilutions of 1 in 

 6000 to 1 in 33,000, whilst pubenilonic acid is less effec- 

 tive, inhibiting at 1 in 6000 only. They liave little effect 

 on Gram -negative organisms. 



Pyocyanase. — Pseudomonas ceruginosa (B. pyo- 

 cyaneus), wliich was among the earliest of organisms 

 shown to produce antibiotic substances, forms pyo- 

 cyanase, pyocyanin and a-hydroxy-phenazine (hemi- 

 pyocyanin). Pyocyanase is l3rtic to many bacteria, 

 such as E. coli, Ehertliella typhosa, C. dijohtherice, V. 

 comma, streptococci and staphylococci, and also detoxifies 

 the toxins of CI. tetam and other bacteria very rapidly, 

 a property also possessed by sodium lauryl sulphate 

 and zephiran (a sulphonated mixture of the fatty acids, 

 Cg to Ci7, contained in coconut oil). 



Pyocyanase, in spite of its heat stability, was at one 

 time thought to be an enzyme attacking nucleic acids 

 but it is now regarded as being of lipoidal nature, the 

 activity depending largely on the presence of unsaturated 

 fatty acids ; it is said to contain a phosphatide and 

 free fat in addition. The facts that it is soluble in ether, 

 chloroform a;nd l^enzene and that its activity is not much 

 affected by changes in temperature between and 37 °C. 

 are not in accord with the view that pyocyanase is an 

 enzyme. It has been obtained as a colourless oil forming 

 an ether soluble lead salt, so that it is probably an 

 unsaturated fatty acid. 



Pyocyanin. — The chloroform soluble blue pigment, 

 pyocyanin, produced by Ps. ceruginosa, has been shown 

 to be a phenazonium compound : — 



