Inhibition of Utilization of Glutamic Acid by Lactobacillus arabinosus.

1. Ten compounds were tested for inhibition of utilization of glutamic acid and glutamine by Lactobacillus arabinosus. 2. DL-α-methylglutamic acid and one of the diastereoisomeric racemates of β-hydroxyglutamic acid were potent competitive inhibitors of glutamic acid utilization. None of the compounds tested was a glutamine inhibitor. 3. The results indicated that the two active compounds prevented the synthesis of glutamine from glutamic acid by the bacteria. 4. Experiments in which the time-course of growth was followed showed that under certain conditions the inhibition by α-methylglutamic acid could be overcome. A possible explanation was suggested for this finding and the importance of taking readings at several time intervals was emphasized.