Waksman — 148 — Actinomycetes 



air which had access to the rock, either in a native state or during the 

 handling in preparing the plates. 



Occurrence of Actinomycetes in Foodstuffs:— Actinomycetes, 

 chiefly forms producing aerial mycelium, are present abundandy on the 

 surface of various fresh and dried food materials. Whenever actinomy- 

 cetes have an opportunity to develop upon such materials, especially 

 during storage, they may cause considerable damage through formation 

 of typical earthy odors that impart to the foodstuffs undesirable flavors. 

 It is particularly interesting to note that actinomycetes are capable of 

 developing upon foodstuffs under conditions not very favorable to molds 

 and bacteria, namely, at fairly high temperatures and at low moisture 

 contents. Whenever foodstuff^s are exposed, under aerobic conditions, 

 at a moisture content which is suboptimum for development of other 

 spoilage-producing microorganisms and at temperatures which are too 

 high for such development, they are subject to attack by actinomycetes. 



Only very few food materials have received attention from this point 

 of view. It is sufficient to mention, for example, the cacao bean. Sev- 

 eral cultures of Streftomyces were isolated from beans received from 

 Nigeria (55) and from cacao produced in the Dominican Republic 

 (69). The mustiness of the beans was ascribed to several species de- 

 scribed as A. alhus and as A. cacaoi. Milk is also subject occasionallv 

 to spoilage by actinomycetes, but this problem, as well, has not been 

 studied systematically (117). 



Occurrence of Actinomycetes in Animal Systems:— Aside from 

 the stricdy pathogenic forms, actinomycetes are frequentlv found in 

 various organs of animals. An organism described as Streftomyces 

 rhodvii has been isolated from the insect Rhodniiis 'proUxus reared in 

 the laboratory (45). This organism is not transmitted through the egg 

 but is taken up bv the young nymph from the environment, such as the 

 contaminated surface of the egg; more often it is transmitted to the in- 

 sect by the dry excreta of other members of the species. The insect has 

 been reared free from the actinomyces by sterilizing the surface of the egg 

 and feeding the adult with suitable precautions. These sterile insects 

 grow and moult normally only for a certain period. Ver}^ few of the 

 insects that have been reared free from the actinomyces become adult, 

 and those few are usually incapable of reproduction. Normal growth, 

 moulting, and egg production by these insects are resumed when they 

 are reinoculated with the actinomyces. 



