178 CHEMICAL NATURE OF ANTIBIOTIC SUBSTANCES 



2. Ci3 group: CjaHioONg — pyocyanin 



3. C21 group: C2iH37_390i2N7 — streptomycin 



4. C34 group: C34H4(;04N2 — pyo II 



5. C41 group: C4iH5gOiiN8 — actinomycin 



6. Ci4e group: High molecular weight compounds, such as grami- 



cidin and tyrocidine; diplococcin may also be in- 

 cluded in this group 



III. Compounds containing C, H, O, N, and S 



1. C9+, namely the penicillin group of compounds which is desig- 

 nated by the formula C9H11O4SN2.R 



2. Ci3 group: C13H14O4N0S0 — gliotoxin 



IV. Other compounds, many of which have as yet not been fully identi- 



fied. Here belongs ustin, C19H15O5CI3. 



On the basis of their toxicity to animals, antibiotic substances may 

 also be divided into three groups: 



Compounds that are nontoxic or but slightly toxic ; here belong penicillin, 

 streptomycin, flavicin, polyporin, and actinomycetin 



Compounds of limited toxicity, including gramicidin, tyrocidine, citrinin, 

 streptothricin, and fumigacin 



Highly toxic compounds, such as actinomycin, gliotoxin, aspergillic acid, 

 and clavacin 



Many of the antibiotic substances are thermostable, others are ther- 

 molablle ; some pass readily through Seitz and other filters, others are 

 adsorbed. The various methods of isolation of these substances are based 

 upon their chemical nature, solubility, and properties of adsorption. 



SUBSTANCES PRODUCED BY BACTERIA 



Lifoids and Pigments 



Ps. aeruginosa, discovered by Gessard in 1882 (329), and formerly 

 known under the names of Bacterium fyocyaneum and Bacillus fyo- 

 cyaneusy produces several antibiotic agents, the colorless lipid pyocya- 

 nase, the pigment pyocyanin, and an alcoholic extract of the bacterial 

 cells. 



Pyocyanase, the first antibiotic substance to be isolated, has had a 



