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A total of 46 glutamate-degrading strains of the genus Clostridium, including 36 new isolates, were examined for deoxyribonucleic acid (DNA)-DNA homology, protein patterns produced by polyacrylamide gel electrophoresis, and physiological characteristics in order to determine the differences between Clostridium cochleurium and "Clostridium tetunomorphum." Thirty-four newly isolated strains could be assigned to the "C.tetunomorphum" group; two strains were classified as nontoxigenic Clostridium tetuni strains. The levels of DNA-DNA homology between C. cochleurium and "C. tetunomorphum" were only 10 to 19%, and the protein patterns showed that there were great differences between both groups and other glutamate-degrading species.Biochemical tests supported these results. In contrast to C. cochleurium, all "C. tetunomorphum" strains fermented carbohydrates (at least glucose and maltose); they also produced lipase and degraded ethanolamine. Moreover, C. cochleurium, like other glutamate-degrading species, needed a higher concentration of yeast extract than "C. tetunomorphum" when it was grown on glutamate. On the basis of our results we propose C. tetunomorphum sp. nov., nom. rev. The type strain is strain NCTC 543 (= DSM 4474).Formerly, the classical glutamate-fermenting clostridial species included Clostridium cochlearium (Douglas, Fleming, and Colebrook 1919) Bergey, Harrison, Breed, Hammer, and Huntoon 1923; Clostridium tetanomorphum" (Bulloch,