Effects of Reduced Citrate Synthase Activity and Feedback-resistant Phosphoenolpyruvate Carboxylase on Lysine Productivities of Brevibacterium flavum Mutants(Microbiology & Fermentation Industry)

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In order to re-examine the effects of reduced citrate synthase activity (designated as CS^L) and feedback-resistant phosphoenolpyruvate carboxylase (PC^R) on the lysine productivities of mutants with feedback-resistant aspartokinase (AK) (AK^R), six AK^R lysine producers were derived from Brevibacterium fiavum No. 15-8 with the CS^L and PC^R characters and isolated as mutants resistant to S-(2-aminoethyl)-L-cysteine plus threonine on the medium containing acetate plus pyruvate as carbon sources. These mutants produced more than 40 g/l of lysine as its HCl salt in the medium containing 10% glucose. In particular, strain No. 664-7 with normally active and completely feedback-resistant AK produced 45 g/l of lysine, whereas an AK^R lysine producer, FA1-30, derived directly from wild strain No. 2247 produced only 20 g/l at maximum. A homoserine dehydrogenase-defective (HD^-) mutant, H-3-4, with the CS^L and PC^R characters also showed higher lysine productivity, 41 g/l, than an HD^- mutant, H1013, which was derived directly from the wild strain and produced 35g/l of lysine. From the above results, it was concluded that the CS^L and PC^R characters were effective for enhancement of the lysine productivities of both AK^Rand HD^- type producers.
社団法人日本農芸化学会の論文
1988-02-23