Production of L-Lysine by Alanine Auxotrophs Derived from AEC Resistant Mutant of Brevibacterium lactofermentum

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Abstract
Relationships between L-lysine productivity and the formation of alanine in B. lactofermentum were investigated. Alanine can be formed from pyruvate by transaminase with L-amino acid, and directly from aspartate in the presence of .alpha.-ketoglutarate and L-leucine. The latter suggests that aspartate .beta.-decarboxylase may contribute to the formation of L-alanine. However, this activity is about 1/20 .apprx. 1/50 of transaminase activity. Productivity of L-lysine was inversely proportional to the level of pyruvate-L-amino acid transaminase. It was confirmed by the derivation of alanine auxotrophs from AJ3445 (AEC [S-(2-amino ethyl) L-cysteine resistant]). The best L-lysine producer, AJ3799, accumulated 39 mg/ml of L-lysine and lacked pyruvate-L-amino acid transaminase.