Chapter V — 91 — Metabolism 



The optimum temperature for the production of streptothricin by 

 S. Javenduhe (452) Hes between 20° and 28°C.; at 37°C. very Httle of 

 the antibiotic is produced. 



The course of growth of an actinomyces, consumption of energy 

 and metabohc changes, as influenced by different sources of nitrogen 

 are brought out in Tables 16 and 17. 



Metabolism of Anaerobic Actinomycetes:— As compared to the 

 aerobic actinomycetes, the anaerobic forms show only limited growth 

 and biochemical activity. According to Erikson, they exert no pro- 

 teolytic action on egg or serum-containing media; they do not clot or 

 hydrolyze milk and, in fact, rarely grow on it; they seldom grow on 

 gelatin, and when there is a little flaky growth the tubes when cooled 

 are found not to have been liquefied; they have little or no hemolytic 

 action on blood broth or blood agar. Certain strains isolated from 

 human infections have been found to show a slight degree of hemolysis 

 on blood-agar plates at different times, but not consistently. They do 

 not produce soluble pigments on protein media or insoluble pigments 

 in their growth. 



Fermentation of sugars by organisms belonging to the genus Acti- 

 nomyces is not accompanied by gas formation. This reaction is fairly 

 constant. Glucose is the most readily fermentable sugar; maltose, lac- 

 tose, and sucrose come second and are fermented within a comparatively 

 short time by all strains; positive or negative reactions with salicin 

 and mannitol have been found of value in differentiating strains, such 

 as human and bovine (112). 



A. hovis was reported by Rosebury (367) to have a limited toler- 

 ance for oxygen, which varies, however, among strains. The optimum 

 temperature for this organisim is 37°C., and optimum pH is 7.2 to 7.6. 

 Although A. hovis grows in the absence of a carbohydrate, it is greatly 

 favored by the presence of glucose. It produces acid from carbohy- 

 drates. 



A. hovis is killed by heating at 62° to 64° C. for 3 to 10 minutes. 

 Like aerobic actinomycetes, it apparently survives drying for a long 

 time, particularly when kept at low temperatures. Lieske, however, 

 reported (260) that anaerobic forms are very sensitive to drying, being 

 unable to survive even for one day. 



Production of Odors:— Most of the aerobic actinomycetes are 

 characterized by the production of a specific odor, which is typical of 

 freshly plowed soil or of composts. This odor is musty, or earthy, and 

 occasionally fruity, in nature. Rullmann (373) believed that the 

 odor is characteristic only of a single species, which he designated as 

 A. odorifer. According to Lieske, only those aerobic forms that pro- 

 dijce chalky white aerial mycelium with round spores are capable of 

 forming this odor; the nonsporulating forms of the Nocardia type and 



