PROTEOLYTIC ACTIVITIES OF SOIL MICROORGANISMS 479 



as for the following organisms can be found in another place 

 (Waksman, 1916). . 



Aspergillus ochraceus Wilhelm. This organism was isolated 

 from a New Jersey Alloway clay soil, which was under tunothy 

 at the time of isolation. 



Aspergillus fuscus Schiemann. 



Aspergillus clavatus Desmasieres. 



Citromyces glaber Wehmer. 



Penicillium chrysogenum Thom. 



Acti7iomyces n. sp. penicilloides Waksman and Curtis. A lull 

 description of this organism will appear soon. 



Actinomyces molaceus-ruher Waksman and Curtis. 



Actinomyces diastaticus (Krainsky) Waksman and Curtis. 



Bacterium mycoides Fliigge, obtained from Dr. C. B. Lipman, of 

 the University of California. All the other organisms were 

 isolated by the writer from different soils. 



Methods used 



The organisms were grown on Czapek's' solution composed as 

 follows: NaNOs 2 grams, K2HPO4 1 gram, KCl 0.5 gram 

 MgS04 0.5 gram, FeS04 0.01 gram, cane sugar 30 grams, distilled 

 water 1000 cc. Another medium was also used, by substituting 

 peptone or casein for the NaNOa, or for both the nitrate and 

 cane sugar. The media were distributed in 100 cc. portions m 

 200 cc. Erlenmeyer flasks, which were plugged and sterilized for 

 fifteen minutes at 15 pounds pressure; they were then inocu- 

 lated with the proper organisms and incubated at 28°C. At 

 the end of the proper incubation period, the cultures were 

 filtered through filter paper and the filtrates used for the deter- 

 mination of ammonia and amino nitrogen. The aeration method 

 of Folin (1902) was used for ammonia determinations, continuing 

 the aeration for three hours, since a shorter period of time did 

 not liberate all the ammonia. In certain determinations,, after 

 all the ammonia had been removed by the use of NagCOs, 1 gram 

 NaOH and 10 grams NaCl were added and aeration continued 

 for one hour more. The use of NaOH and NaCl was recom- 



