niS'I'IMIU'IMoX I\ NA'ITHK 



43 



sen. Salmon caught in sonic of tli(> richest 

 salmon rivers in (Jroat Britain wcvv found 

 contaminated with this odor, which l)ccanu' 

 so noticeable when the fish were boiled that 

 they were inedible. The odoriferous sub- 

 stance was soluble in water and volatile in 

 steam. The river water itself where the i)ar- 

 ticular fish were caught also had this 

 "earthy" odor. It was strong along the 

 banks where mud overgrown with reeds had 

 accumulated. Thaysen plated out the sub- 

 merged ri\-er mud; he suggested that the 

 actinomycete colonies thus obtained were 

 not derived from spores but represented ac- 

 tive "foci" of growth, as shown in Table 9. 

 On comparing similar numbers from sub- 

 merged material in a river that did not have 

 the "earthy" odor, Thaysen found 13,000 

 actinomycete colonies per gram of sub- 

 merged mud, 52,000 per gram of water- 

 logged vegetation, and 244,000 per gram of 

 \egetation removed from the dry bank of 

 the river. None of these cultures was of the 

 odoriferous type. In the contaminated river, 

 the actinomycetes represented "an abnor- 

 mally high proportion in the microflora." 



Among the other food products subject to 

 considerable damage from the occurrence of 

 actinomycetes is the cacao bean. In 1927 

 Ciferri undertook a study of the causative 

 agents of the musty odor of these beans in 

 the Dominican Republic. He found this odor 

 to be associated with the occurrence of ac- 

 tinomycetes; the commonest form was a 

 variety of S. albus. Bunting, in 1932, isolated 

 three cultures of actinomycetes, described 

 under a species name S. cacaoi. The pungent 

 musty odor of the cacao was found to be 

 caused by these organisms. 



According to Haines (1932), actinomy- 

 cetes occur commonly in commercial cold 

 stores. They were isolated from the walls 

 and especially from the sti'aw on the floor 

 of the stores. 



Among the other food products that may 

 be contaminated with actinomycetes, it is 



Tabi.k 



Xiimhrr o/ (irtinofni/celr "fori" in sulnncrdrd river 

 Ixink in 11(1 (Th!ivs(Mi) 



Left bank of river, odor 

 strong 



Right bank of river, 

 odor slight 



Yards bolow tidal limit 



ll'(» 200 220 600 1100 120 220 000 1100 



Thousands of actinomycetes per gm of material 



280 220 609 330 400 8 0:1(?) 500 362 



sufficient to mention rum, as first pointed 

 out by Price-Jones. 



Occurrence of Actinomycetes on and in 

 Plants 



Actinomycetes occur universally on the 

 surface of plants and sometimes even in var- 

 ious parts of the plants themselves. This is 

 true, for example, of potatoes. Some of these 

 organisms are saprophytic in nature and 

 others are pathogenic, being responsible for 

 the causation of specific plant diseases, as 

 pointed out in Chapter 18. 



Various theories have been proposed con- 

 cerning the function of the actinomycetes in 

 the plants, since they are known to occur in 

 the outer layers of roots and tubers. Bei- 

 jerinck found various plants to be superfi- 

 cially infected with actinomycetes. In 1903, 

 Petri isolated an actinomycete culture from 

 the roots of strawberry plants; although 

 this organism could be inoculated into fresh 

 plants, it was considered to be a saprophyte, 

 since the plants were in a healthy state even 

 after 6 months. Lutman observed actino- 

 mycete filaments growing along the cell 

 walls of potatoes and other plants; the fila- 

 ments were branching and were passing into 

 the cell lumen, twisting and bending in tor- 

 tuous paths; the stems above ground, the 

 leaves, and the flowers were also completely 

 infected. Lutman postulated the theory that 

 the cells of the actinomycetes take part in 



