308 PRINCIPLES OF SOIL MICROBIOLOGY 



(b) Growth on synthetic agar colorless; aerial mycelium 



thin, rose-colored A. roseus 



(c) Growth on carrot and potato rapidly spreading, envelop- 



ing the whole plug and destroying it rapidly, plug 

 becoming colored deeply brown A. griseolus 



(d) Red (vinaceous) soluble pigment on synthetic agar, often 



turning red-brown; white aerial mycelium 



A. erythreus 

 B. No soluble pigment produced on gelatin or other protein media: 



I. Species strongly proteolytic: gelatin liquefied rapidly, milk clotted 



and peptonized rapidly. 



2. Brown soluble pigment on synthetic agar; diastatic action very 

 strong A . diastaticus 



2. Rapid liquefaction of coagulated blood serum, strong hemolysis 



of blood (37°); aerial mycelium on synthetic agar has a tea- 

 green tinge A. griseus 



3. Yellowish green growth on starch plate with pinkish aerial my- 



celium; citron-yellow growth on synthetic agar A. citreus 



4. Greenish-yellow growth on synthetic agar, gray powdery aerial 



mycelium, greenish-yellow soluble pigment A, flavovirens 



5. Colorless growth on synthetic agar, white to grayish aerial my- 



celium, no spiral formation; thin reddish-brown growth on 

 potato plug (purplish zone on plug) ; faint yellow pigment may 

 develop on gelatin, blood and egg-media A. poolcnsis 



6. Buff colored growth on glucose agar, violet-gray aerial my- 



celium; yellow growth on synthetic agar with light drab 

 aerial mycelium; rapid destruction of potato plug 



A . olivaceus 



7. Very scant colorless growth with scant white aerial mycelium 



on synthetic agar and on synthetic media containing NaNCh 

 as a source of nitrogen; abundant brown growth with white 

 aerial mycelium and soluble brown pigment on glucose agar; 

 growth on potato plug greenish turning black.. .A. gelaticus 



II. Proteolytic action weak: 



1. Soluble pigment produced on synthetic agar: 



(a) Pigment blue or blue-black A. violaceus-cacsari 



(b) Pigment brown to almost black on all synthetic media 



with NaN0 3 as a source of nitrogen A. exfolmtus 



2. No soluble pigment on synthetic agar, although growth is colored : 



(a) Growth turning black, diastatic action very strong: 



(a') Growth on synthetic agar scant with abundant 

 spirals in aerial mycelium, no invertase pro- 

 duction A. rutgersensis 



(b') No spirals on synthetic agar, characteristic green 

 colored growth on protein-glycerin media 



A. lipmanii 



(c') None or scant aerial mycelium on all media; growth 



abundant on synthetic agar (invertase positive); 



