120 ACTINOMYCETES AS ANTAGONISTS 



which, like Ps. aeruginosa, are rather resistant to streptothricin (460a, 



795)- 



A^. gardneri produces an active bacteriostatic substance which has been 

 designated as proactinomycin (309). Its bacteriostatic spectrum is 

 shown in Table 24. It is produced both on synthetic and organic media. 

 Its action is largely directed against gram-positive bacteria, although to 

 a more limited extent than that of actinomycin. Its isolation and chemi- 

 cal nature are brought out later (p. 175). 



TABLE 24. BACTERIOSTATIC EFFECT OF PROACTINOMYCIN 



APPROXIMATE DILUTION OF 

 MATERIAL IN MILLILITERS 

 ORGANISM GIVING HIGHEST EFFECT 



D . fneumoniae 1,500,000 



S.fyogenes 500,000 



S. aureus 500,000 



A^. meningitidis 500,000 



B. anthracis 500,000 



F. cholerae 6,000 



5. tyfhiy S. paratyphi B, Shigella, E. coli 2,000 



From Gardner and Chain (309). 



S. alhus produces a bacteriolytic substance designated as actinomyce- 

 tinj it has been described on page 107. This substance is a protein and 

 is enzymatic in nature. It has not yet been isolated in a pure state. Its 

 lytic action was visualized by Welsch (971 ) as a two-step reaction: first, 

 the susceptible cells are killed by the selectively bactericidal lipoid j sec- 

 ond, those dead cells are dissolved by the bacteriolytic enzyme, which 

 alone is responsible for the lysis of heat-killed bacteria. The phenome- 

 non does not take place in complex culture-media, since the bactericidal 

 action of the lipoid is greatly impaired under those conditions j the pres- 

 ence of living actinomyces is generally necessary, since free lipoid 

 should be secreted in the susceptible suspension. 



Wieringa and Wiebols (981) observed that certain actinomycetes 

 can produce lytic agents that are capable of exerting a lytic effect not 

 only upon the actinomycetes themselves but also upon other organisms. 



