The effect of temperature on the nutritional requirements of facultative and obligate thermophilic bacteria.

The first report dealing with the effect of temperature on the nutritional requirements of microorgsms seems to be that of Mitchell and Houlahan (1946a). In the course of their genetic studies on Neurospora a mutant strain was isolated which required riboflavin for growth. They noted that this requirement was a function of the incubation temperature. When the mutant was grown at temperatures below 25 C, it synthesized riboflavin at a rate approaching that of the wild type strain while at temperatures above 28 C an external source of the vitamin was necessary. Since this report papers have appeared describing temperature sensitive mutants of Neurospora requiring adenine (Mitchell and Houlahan, 1946b; McElroy and Mitchell, 1946), uridine (Houlahan and Mitchell, 1947), and sulfanilamide (Emerson, 1947). Maas (1950) has reported on a temperature sensitive mutant of Escherichia coli requiring pantothenic acid. Similar studies of the effect of the temperature of incubation on nutritional requirements have been made on nonmutant strains of Lactobacillus arabinosus by Borek and Waelsch (1951), on Esherichia coli by Ware (1951), and on Pasteurella pestis by Hills and Spurr (1952). In general the findings of these workers have shown that at the higher incubation temperatures the organisms under study required additional metabolites for growth. A search of the literature revealed a paucity of information concerning the nutritional requirements of thermophilic bacteria. Cleverdon et al. (1949a) studied the vitamin requirements of a strain of Bacillu8 coagukn8 at 37 C and 55 C. Employing a vitamin-free casein hydrolyzate