Studies on thermophilic sulfate reducing bacteria. I. Identification of Sporovibrio desulfuricans as Clostridium nigrificans.

Elion (1924) was the first to isolate a thermophilic sulfate reducing bacterium in pure culture. He named the organism Vibrio thermodesulfuricans, and reported that it was capable of sulfate reduction betveen 30 and 65 C, wvith an optimum of 55 C. Baars (1930) and Kluyver and Baars (1932) reisolated V. thermodesulfuricans, and carried out a comparative study of this organism and Vibrio desulfuricans. They reported that it was possible to adapt cultures of V. desulfuricans, initially capable of growth only at 30 C, to grow up to 55 C by gradually increasing the incubation temperature. The reverse phenomenon was also demonstrated with V. thermodesulfuricans. They concluded that V. thermodesulfuricans should be regarded as a temperature adapted strain of V. desulfuricans. The sulfate reducing bacteria are now placed in the genus Desulfovibrio, created by Kluyver and Van Niel (1936). Starkey (1938) isolated cultures from sewage, mud, and soil at 30 and 55 C. Contrary to the findings of earlier investigators, all of the cultures isolated at 55 C were large, slightlv curved, spore-forming rods, while those isolated at 30 C were typical asporogenous short vibrios. The cultures isolated at 30 C were motile by a rapid progressive movement and had one (or two) polar flagellum(a). Those isolated at 55 C had a rotating motility with only a slight progressive movement, and possessed from 1 to 10 or more flagella scattered around the cell. Cultures isolated at 30 C failed to grow when transferred directly to 55 C, but the cultures isolated at 55 C