STUDIES ON THE INHIBITION OF GROWTH OF ESCHERICHIA COLI BY NORMAL AMINOBUTYRIC ACIDS

Among the normal butyric acids with an io group substituted on either the a, ,I, , or a,y(diamino) positions, a-aminobutyric acid has the paradoxical effect within the same range of concentrations of being an inhibitor of growth (Gladstone, 1939; Rowley, 1953; Fairley, 1954), purine biosynthesis (Gots and Love, 1954) and g3-alanine utilization (Nielsen et al., 1944), and an intermediate in isoleucine (Umbarger, 1955; Adelberg, 1955) and methionine biosynthesis (Gots and Koh, 1950; Kalan and Ceithaml, 1954; Schwartz and Shapiro, 1954). Diaminobutyric acid is a unique constituent of polypeptide antibiotics (Bricas and Fromageot, 1953) and ,-aminobutyric acid inhibits pantothenate synthesis in yeast (Nielsen et al., 1944). The metabolic function of both is unknown. No inhibitory role has been ascribed to y-aminobutyric acid, an intermediate in glutamic acid biosynthesis. In the present study these compounds are compared for their inhibitory effect on the growth of Escherichia coli strain B, and several related auxotrophs.1 The prevention of the inhibitory effects caused by a, ,B, or diaminobutyric acids are described. Data are also presented suggesting that at certain concentrations, a-aminobutyric acid creates an additional general metabolic disturbance due to displacement of the essential cation potassium.