Waksman — 146 — Actinomycetes 



while still covered with ice, contained 12,500 cells of Microinonospora 

 per milliliter of wet mud, or 16 per cent of the total microbiological pop- 

 ulation. After the ice had left, the numbers increased to 100,000 or 

 45 per cent; they reached 120,000 to 250,000 or 11 to 22 per cent in 

 June. This relationship was found to hold true, not only for the shal- 

 low, but also for the deeper bottom deposits, where the proportion of 

 members of the Microinonospora group to the total population might 

 even be greater. The microbiological population of the edge of the 

 lake, the beach area, tended to approach that of normal soil, with various 

 other actinomycetes as well as fungi making their appearances. The 

 genus Micromonosfora thus appears to form a group of microorganisms 

 which are indigenous inhabitants of lake waters and lake water deposits. 



Thaysen (417) found as many as 8,400 to 609,000 actinomycetes 

 per gram of submerged river mud, 120 to 1,100 meters below the tidal 

 line. There was a definite parallelism between the strength of the 

 earthy odor in the mud and in the water and the abundance of actino- 

 mycetes. These organisms were believed to be concerned with the de- 

 struction of the submerged reeds, since the bases of the reeds yielded the 

 greatest numbers of actinomycetes. 



PuTiLiNA (351) made a detailed study of the abundance of actino- 

 mycetes in the waters and sediments of the Don basin, for a distance of 

 120 km. The numbers of these organisms in the bottom material were 

 10 to 1,000 times greater than those in the water. These actinomycetes 

 were believed to be responsible for the undesirable odors imparted to the 

 Don waters. Similar odors were produced when the isolated cultures 

 were artificially cultivated. 



Egorova and Issatchenko (102, 182) also reported an extensive 

 population of actinomycetes in river bottom deposits, the numbers vary- 

 ing from 36,585 to more than a million per gram of dry material. Large 

 numbers w^ere found even at depths of 20 cm. Only few actinomycetes 

 (100 per milliliter) were found in the water itself. These organisms 

 were largely of the aerobic, sporulating tvpes. When some of the water 

 and a layer of bottom material were placed in cylinders, sterilized, and 

 inoculated with pure cultures of actinomycetes, excellent growth was 

 obtained in a short time. This suggested the aqueous existence of these 

 organisms. The earthy smell and the unpleasant flavor of the Moskau 

 river water was ascribed to the multiplication of these actinomvcetes in 

 the bottom muds, especially during the summer and fall months, when 

 extensive multiplication of these organisms occurs at the expense of the 

 abundant plant remains. 



Actinomycetes occur very extensively in peat bogs, especially in the 

 sedge and reed peats, which are less acid in reaction. Their presence 

 in these habitats is limited largely to the upper aerated or partly aerated 

 layers, as shown in Table 37. When the peat bog is drained, actino- 

 mycetes develop extensively. 



The occurrence of actinomycetes on submerged surfaces in sea 



