DTSTHllU'TIoX T\ \ ATTRK 



39 



fouml i)('i- milliliter of lake imul, ninount iiiii 

 to 4") jH'i" ci'iit ol (he tt)l;il iniciohial popula- 

 tion. \\'\\h an iiuTcaso in the depth of the 

 l)ottoni inatcM'ial there was an increase in 

 tlie nunilnTs and percentaj^es (up to (>() to 

 70 per cent) of actinoniycetes. Tlie conclu- 

 sion was readied that the ,a;iMuis M irromoim- 

 sporo represents a tiiil\' inthgenous ji;i-oup of 

 microbial inhabitants of waters and bottom 

 deposits of inland lakes. Since thes(> organ- 

 isms are aerobic and grow very slowly, it was 

 at first iH'Heved that their role in the decom- 

 position of organic matter in water basins 

 was only a minor one. Their ability to attack 

 resistant organic materials, such as hgnins, 

 suggested, however, a potentially important 

 function for these organisms. 



Erikson isolated 10 strains of Micromono- 

 spora from lake mud and lake water. These 

 were capable of growing on a large variety 

 of resistant organic compounds, such as 

 chitin, cellulose, and, to a lesser degree, lig- 

 nin. It was suggested that these organisms 

 play a significant part in lacustrine ecology, 

 being adapted to life under aquatic condi- 

 tions and being able to utilize resistant sub- 

 stances of the type found in lake mud. 



Actinoniycetes are also found in river wa- 

 ters and in river bottoms. As a consequence, 

 a serious problem may arise, namely, the im- 

 parting to the water of the odor character- 

 istic of cultures of actinoniycetes. This odor 

 renders the water unsuitable for drinking 

 purposes. Adams drew attention to the fact 

 that the ''earthy" taste of the water of the 

 rWer Nile was due to actinoniycetes that in- 

 habit or "contaminate" the water. Burger 

 and Thomas suggested that the peculiar 

 taste of the water was due to the decomposi- 

 tion of plants growing in the waters, the ac- 

 tinoniycetes forming merely a small part of 

 the total microbiological population. 



The role of the actinoniycetes in the pro- 

 duction of odoriferous substances in the wa- 

 ter has received considerable attention. 



Tulilina examined the aliimdance of (hese 

 organisms in the waters and sediments of 

 the Don basin. Their numl)ers in the bottom 

 material wei-e 10 to lOOO limes gi'eater than 

 those in the water. They were belie\-ed to 

 l)e responsible for the unpalatable odors im- 

 parted to the ])oii waters. When the organ- 

 isms were isolated in pure culture, similar 

 odors were j)roduce(l in artificial media. 

 l']gorova and Issatchenko also found an ex- 

 tensive population of actinoniycetes in river 

 bottom deposits. The numbers varicxl from 

 30, 585 to more than a million per gram of 

 dry material. Larg(^ luiintx-rs were r(>coi(led 

 even at a depth of 20 cm. ( )nly few organisms 

 were found in the water itself. When some 

 of the water and a layei- of bottom material 

 were placed in cylinders, sterilized, and inoc- 

 ulated with pure cultures of actinomycetes, 

 excellent growth was obtained in a short 

 time. The earthy smell and the unpleasant 

 fla\'or of the Moscow ri\'er water was as- 

 cribed to the multiplication of actinomycetes 

 in the bottom muds, especially during the 

 summer and fall months. They were largely 

 of the streptomyces type. The sandy soils 

 along the river banks contained a larger 

 number of actinomycetes. The odor pro- 

 duced by them is washed out by rains and 

 carried into the river. This takes place espe- 

 cially after the soil undergoes a spell of dry 

 or freezing w-eather. The numbers of actino- 

 mycetes increase particularly in autumn. 

 The passage of the odoriferous substance 

 into the w^ater depends also on the nature 

 and adsorbing capacity of the bottom mate- 

 rial : sandy bottoms give a marked odor, and 

 clay bottoms only little odor because of its 

 adsorption on the clay (Issatchenko). Thay- 

 sen has also made a study of the relation of 

 actinomycetes to the odor of river water, as 

 shown later in this chapter. Numerous other 

 studies have been made on the occurrence of 

 actinoniycetes in difTerent kinds of waters, 

 to which they can impart odors and tastes 



