THE OXIDATION OF GLUTAMIC ACID BY BRUCELLA ABORTUS'

The oxidation of glutamic acid by avirulent strains of Brucella abortus is the most rapid respiratory process thus far studied in this species (Gerhardt et al., 1950a). Furthermore, glutamic acid will serve as the sole source of both carbon and nitrogen for all strains of B. abortus which have been tested (Gerhardt et al., 1950b). Glutamic acid is important in the synthesis of other amino acids by transamination (Altenbern and Housewright, 1951), and the evidence thus far indicates that the reductive amination of a-ketoglutaric acid to glutamic acid may be the chief means of amino group synthesis. The purpose of this study was to determine the products of the oxidation of glutamic acid and to investigate the intermediate steps. METHODS The conditions used in this laboratory for growing and harvesting cells of B. abortus have been reported in detail previously (Gerhardt et al., 1950a). B. abortus, strain 11, a relatively avirulent smooth strain closely related meta-bolically to strain 19, was used throughout this investigation. Metabolic reactions were followed manometrically at 34 C and at pH 5.5 or 6.8 buffered with 0.067 M potassium phosphate. The cells were killed either with flowing steam or sulfuric acid and were removed by centrifugation. Amino acids were determined by the chromato-graphic methods of Housewright and Thorne (1950) and of Stein and Moore (1950), ammonia by direct nesslerization, and total nitrogen by a modification of the method of Johnson (1941). Total carbon was determined by wet combustion (van Slyke and Folch, 1940, as modified by Stutz and Burris, 1951) and citri