PATHOGENIC SPECIES OF THERMOPHILIC 



AND THERMOTOLERANT FUNGI 



IN REACTOR EFFLUENTS 



OF THE SAVANNAH RIVER PLANT 



M. R. TANSEY* and C. B. FLIERMANSf 



*Department of Biology, Indiana University, Bloom4ngton, Indiana; and 



tSavannah River Laboratory, Aiken, South Carolina 



ABSTRACT 



The growth, occurrence, and distribution of thermophilic and thermotolerant 

 fungi were studied in effluents from Savannah River Plant nuclear reactors. 

 Samples of foam, water, microbial mats, plant debris, air, and soils from sites of 

 elevated and ambient temperatures were analyzed by direct microscopic 

 examination and by quantitative plating. Analyses revealed that, except for 

 Dactylaria gallopaua, populations of thermotolerant and thermophilic fungi were 

 not significantly different at elevated and ambient temperature sites. Dactylaria 

 gallopaua, a thermotolerant fungus that causes epidemic encephalitis in poultry, 

 is abundant in the microbial mats, in foam, and in soils at the edges of the 

 cooling-water effluents. It is directly associated with effluents that have 

 temperatures of 44 C and higher. The evidence suggests that the thermal 

 effluents are responsible for the occurrence of D. gallopaua. 



Among eukaryotic groups of organisms, evolutionary adaptation to 

 growth at high temperature occurs at the extreme degree in the 

 thermophilic and thermotolerant fungi (Tansey and Brock, 1972). 

 Thermophilic fungi are those having a maximum temperature for 

 growth of 50°C or higher and a minimum temperature for growth of 

 20°C. Thermotolerant fungi can grow at 50° C or above and grow 

 well below 20°C (Cooney and Emerson, 1964). When high tempera- 

 tures are relatively constant and coexist with some other environ- 

 mental extreme, as in acid hot springs, a single fungal species occurs 

 and grows (Tansey and Brock, 1973; Belly, Tansey, and Brock, 

 1973). In sun-heated soils and in many other habitats where thermal 

 stresses (both high and low temperatures) coexist with moisture 



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