DISTinHrTIoN I\ NA'ITHI': 



37 



'The addition of orj^auic matter to the soil 

 lias a inarkiHl st iimilatiii<«; (^I'tVct upon the 

 d('\'(>lopnuMit of actinoniycctcs, as illustrated 

 \)\ Waksinaii and Stai'kcy (l!)24). 



One nioiv prol)l(Mn pcM'taininfi; to (he sur- 

 \-i\-al of actinoniycctcs in the soil must ho 

 considci'c'd, namely, the sui\i\al of or<i;an- 

 isnis addotl to the soil. Fousek reported that 

 addition of cultures of actinomyeetes to soils 

 rich in oriianic matt(M- hastencMl decomposi- 

 tion of the humus and inci'eased liberation 

 of the nutrients. It is a well established fact 

 that wluMi lowmoor jx'at soils are freshly 

 draintMl and culti\'ated, actinomyeetes will 

 (kn'clop at a rapid rate in such soils (Waks- 

 man and Purxis, 19o2). If the potato scab 

 organisms are able to make an entrance into 

 peat-rich soils, and potatoes are planted in 

 such soils, the resulting scabby potatoes may 

 play havoc with the crop. If cultures of ac- 

 tinomyeetes are added to ordinary soils, 

 however, they tend to die out rapidly, as 

 demonstrated by Waksman and Woodruff 

 (1940). This has been explained by the com- 

 plex antagonistic interrelations among the 

 various groups of microorganisms inhabiting 

 the soil. 



Among the most important factors con- 

 trolling the abundance of actinomyeetes in 

 the soil, one must recognize, (a) the nature 

 and abundance of the organic matter, (b) 

 the reaction, (c) the relative moisture con- 

 tent, (d) the temperature, (e) the aeration 

 of the soil or the oxygen supply, and, finally, 

 (f) the soil vegetation (Rouatt d at., 1951). 



In general, actinomyeetes are less favored 

 by a higher moisture content than are the 

 bacteria. They are able to grow well at a 

 relatively low moisture, even at 15 to 20 per 

 cent of the moisture-holding capacity of the 

 soil. Most of the bacteria, which grow best 

 at 50 to 65 per cent moisture-holding capac- 

 ity, do not develop at all undei- those condi- 

 tions. 



Although actinomyeetes are as a rule cos- 

 mopolitan in their distril)ution, since they 



ai'c found inii\ rtsally, the spccilic substrate 

 and enxironment greatly influence their na- 

 tui'e. This is true, foi' example, of soils in 

 which suc('essi\-e crops of ])otatoes ha\'e been 

 grown. 



Further studies on the wide disi libution 

 of actinomyeetes in soil have been made by 

 Xegre (Sahara soils), Jensen (19:^0, 1931, 

 HKU, 193()), Waksman (1932), Adachi and 

 Imanuu-a (1933), Ilopf, Strutz (1952), Jag- 

 now (1957), and others. Detaiknl studies of 

 the occurrence in soil of actinomyeetes pos- 

 sessing antagonistic properties against other 

 microorganisms and capable of producing 

 antibiotic substances are presented in Chap- 

 ters 14 and 15. 



Occurrence of Aclinomycetes in the Sea 



Only very few reports are available con- 

 cerning the occurrence of actinomyeetes in 

 sea water and sea bottoms. Their occasional 

 presence in this environment was usually be- 

 lieved to be due to soil contamination, or to 

 their presence on algal material floating on 

 the surface of the sea, or to the fact that 

 the samples of water were obtained near the 

 docks (Zobell and Upham). Sea water en- 

 riched with petroleum hydrocarbons per- 

 mitted the development of nocardias and 

 micromonosporas (Zobell ct al.). 



Humm and Shepard reported (1946) the 

 isolation of several agar-decomposing actino- 

 myeetes from marine material. Some ap- 

 peared to belong to the genus Nocardia and 

 others to Strcpiomijces. Freitas and Bat 

 (1954) also isolated members of these two 

 genera from deteriorating fish nets and cord- 

 age. 



Schwartz and Sielici't and Schwartz (1956) 

 made a detailed study of the occurrence of 

 actinomyeetes in marine sediments. Because 

 of the resistance of these organisms to high 

 salt concentrations, one would expect to find 

 them in such sediments. When filter paper 

 was placed in contact with marine sediments 

 the development of various species of aetino- 



