156 



THE ACTIXOMYCETES, Vol. I 



Kalininko came to the conclusion that the 

 decomposition of rubber in nature is carried 

 out by molds and, especially, by actinomy- 

 cetes. Among the latter organisms, three 

 forms were found to be particularly active, 

 namely, *S'. cocHcolor, S. aurantiacus, and S. 

 longisporus ruber. Further studies on rubber 

 decomposition ha^'e been made by Spence 

 and van Xiel. 



Decomposition of Paraffin Hydrocar- 

 bons 



Biittner established that various aerobic 

 actinomycetes that appear to include species 

 of both Streptomyces and Nocardia are capa- 

 ble of attacking paraffin. A film is formed 

 upon the paraffin. Most of the lost paraffin 

 is recovered as CO 2 . Oxidation of petroleum 

 hydrocarbons by marine organisms was 

 studied by Zobell ct al. See also Chapter 7, 

 for hydrocarbon oxidation by nocardias. 



Production of Odors 



Many actinomycetes, especially species of 

 Streptomyces, are characterized by the pro- 

 duction of a specific odor, which is typical 

 of freshly plowed soil. It is musty, or earthy, 

 and occasionally fruity in nature. Rullmann 

 believed that the odor is characteristic of 

 certain species. According to Lieske, only 

 those aerobic forms that produce chalky 

 white aerial mycelium with round spores are 

 capable of forming this odor; the nonsporu- 

 lating forms of the Nocardia type and those 

 streptomyces that produce cylindrical spores 

 do not give rise to any odor. The presence of 

 carbohydrates in the medium favors odor 

 production. The thermophilic actinomycetes 

 are responsible for the more fruity scents, 

 which arise particularly from young cultures. 

 The odoriferous substance can be extracted 

 from the culture. It is soluble in ether and 

 partly in alcohol. 



Thaysen (1935) found that the odor is 

 produced by certain actinomycetes only 

 under certain conditions of growth and on 



certain media. Gelatin, for example, does 

 not favor the formation of odoriferous sub- 

 stances. 



As is shown in Chapter 3, the odor pro- 

 duced by actinom3^cetes is responsible for a 

 certain type of spoilage of fish that absorb 

 it into their digestive systems, from which 

 it spreads throughout the bodies of the fish. 



Lime Precipitation 



Xadson isolated various actinomycetes 

 from the bottom of a lake characterized by 

 limestone precipitation. He mentioned .4. 

 albus, A. roseolus, and .4. verrucosus, all 

 apparently belonging to the genus Strepto- 

 myces. He considered them as members of 

 the microbiological population active as geo- 

 logical agents. Molisch (1925) also observed 

 cultures of actinomycetes capable of bring- 

 ing about lime precipitation. Colonies grow- 

 ing on media containing Ca acetate, 2 per 

 cent solution, are surrounded by crystals of 

 calcium carbonate. 



Krassilnikov (Issatchenko, 1948) observed 

 the precipitation of CaCOa on roots of plants 

 covered with actinomycetes. In two old cul- 

 tures of actinomycetes isolated from salt 

 lakes, Rubentschik (1948) observed the crys- 

 tallization, in protein media, of CaCOa . 



Nitrification and Nitrate Reduction 



Various reports have been made (Schatz 

 et al.) that certain actinomycetes are able to 

 oxidize ammonia and nitrite to nitrate. Jen- 

 sen (1951) reported that A^. corallina can 

 nitrify up to ()4 per cent of oxime of pyruvic 

 acid in an inorganic salt solution. Glucose 

 inhibited nitrification, by stimulating sjni- 

 thesis of cell material, at a C:N ratio above 

 20:1. In peptone media, Nocardia converted 

 the oxime almost quantitatively to nitrite, 

 the rate of its formation being etjual to that 

 of cell synthesis. 



The reduction of nitrate to nitrite l)y 

 actinomycetes has long been recognized 

 (Salzmann, Joshi, Ghosh et al.). Various 



