Evaluation of the contribution of the tyrosine pathway to the catabolism of phenylalanine inBrevibacterium linens47

The quantitative importance of the 3,4-dihydroxyphenylacetatemeta-cleavage pathway (the principal pathway of tyrosine catabolism) in the catabolism ofl-phenylalanine inBrevibacterium linens 47 was evaluated using tyrosine-negative mutants. Less than 5% of phenylalanine was catabolised through the tyrosine pathway. The results presented show that inB. linens the two structurally analogous amino acids are catabolised principally by separate pathways. Also, the initial pathway of phenylalanine catabolism in this bacterium has been established.