METABOLIC CHARACTERIZATION OF THE GENUS BRUCELLA III.

ABSTRACT

Meyer, Margaret E. (University of California, Davis). Metabolic characterization of the genus Brucella. III. Oxidative metabolism of strains that show anomalous characteristics by conventional determinative methods. J. Bacteriol. 82:401–410. 1961.—The oxidative metabolic patterns were determined on 83 strains of brucellae that had been described as “atypical” because they differed in one or more characteristics or because they had been isolated from an abnormal host (other than the natural reservoir for that species).

Of the 83 strains examined, 44 displayed the metabolic pattern for Brucella melitensis. A comparison was then made between the results of identifying these strains metabolically and by the conventional methods. It was found that a few strains of B. melitensis showed a decreased tolerance to basic fuchsin and thionin, but none of the strains that was identified metabolically as B. melitensis produced H₂S or required CO₂. No biotypes have been reported for this species, since only slight quantitative variation in dye tolerances occurs among strains of B. melitensis, and no metabolic variants were found. It is concluded that B. melitensis is a homogenous species and can be identified with certainty by its oxidative metabolic pattern, irrespective of its host or geographic source.

Of the remaining strains, 38 displayed the metabolic pattern singular for Brucella abortus. Evidence was presented to support the conclusion that in this species the characteristics of dye tolerance, H₂S production, and CO₂ required for initial growth vary independently of each other, and strains that differ from the species description by these criteria can be identified correctly by their oxidative metabolic pattern.

Of the 83 atypical strains examined, 24 were strains of Brucella described as a new species, Brucella intermedia (Renoux). Of these 24 strains, 10 were identified as Brucella melitensis, 13 as Brucella abortus, and one as Brucella suis. Evidence was presented to support the conclusion that B. intermedia (Renoux) cannot be considered as a new species.