Preferential uptake of d-α-aminoadipate from a racemic mixture by an Alcaligenes denitrificans

Abstract

During growth on racemic α-aminoadipate as a sole source of carbon and nitrogen an Alcaligenes denitrificans displayed a two-phase (diauxic) growth not shown by a Pseudomonas putida. Oxidation studies in the presence of chloramphenicol showed that in both growth phases whole cells of A. denitrificans had the ability to oxidize either isomer of α-aminoadipate. These data negated as the physiological basis for diauxic growth a proposal that one isomer was repressing the synthesis of enzymes which transport or degrade the other enantiomer. Growth studies with various ratios of the d- and l-isomers of α-aminoadipate, differentiating one isomer from the other by radioactivity, indicated that diauxic growth resulted from a preferential uptake of d-α-aminoadipate over the l-isomer.