Production of L-phenylalanine by a mutant of Brevibacterium lactofermentum 2256.

Abstract

Excellent L-phenylalanine producers were screened from among tyrosine, methionine doubly auxotrophic and antimetabolite resistant mutants derived from a L-glutamic acid-producing bacterium; Brevibacterium lactofermentum 2256. A selected mutant, Brevibacterium lactofermentum No. 123, produced 21.7mg/ml of L-phenylalanine in 72 hr when 13% glucose was supplied as a carbon source. The accumulation of L-phenylalanine by strain No. 123 became 5.17-fold higher than that by parental strain No. 808. This yield was the highest among those so far reported. The addition of fumaric acid to the culture medium promoted the L-phenylalanine production. Accumulation of other amino acids in the culture broth was negligible compared with that of the main product, L-phenylalanine.