A Study of Certain Members of the Genus Corynebacterium

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Abstract
The morphological, cultural, and biochemical characteristics of 79 cultures belonging to the genus Corynebacterium, isolated from normal and pathologic animal sources, have been studied in an attempt to find improved methods of differentiating between such organisms and thus clarifying their relationships to each other. The wide range of variability exhibited by members of this group necessitates their separation into general groups based on the relative degree of activity exhibited by them, particularly with respect to the following characters: pellicle formation in nutrient broth, alkaline reaction in litmus milk, pigment formation on blood serum slant, reduction of nitrates, hydrogen sulride production, and alkaline reaction in dextrose broth. Three general groups have been suggested as a basis for classifying this type of organism, viz.: Group I[long dash]The C. equi Group[long dash]strains showing a high degree of activity. Pellicle is formed in nutrient broth, final reaction in litmus milk is alkaline, yellow pigment is produced on blood serum slant, nitrates are reduced to nitrites, H2S is produced, and final reaction in dextrose broth is alkaline. Group II[long dash]The Intermediate Group[long dash]strains showing a medium degree of activity. Pellicle is usually formed in nutrient broth, final reaction in litmus milk is usually alkaline, yellow pigment may or may not be produced on blood serum slant, nitrates may or may not be reduced to nitrites, hydrogen sulfide is usually not produced, and final reaction in dextrose broth is weakly acid. Group III[long dash]The C. pyogenes Group[long dash]strains showing a low degree of activity. Pellicle is rarely formed in nutrient broth, final reaction in litmus milk is acid, no yellow pig- ment is produced on blod serum slant, nitrates are not reduced to nitrites, H2S is not formed (most strains do not grow on the medium), and final reaction in dextrose broth is weakly acid.

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