L-Phenylalanine Production by Regulatory Mutants of Excherichia coli K-12

Escherichia coli K-12 대사조절 변이주에 의한 L-페닐알라닌 생산

In order to overproduce L-phenylalanine, various kind of regulatory mutants were isolated from parental Escherichia coli K-12. MWEC 83 Producing 7.4g/l of L-phenylalanine has been derived as a tyrosine and tryptophan double auxotrophic mutant. To produce L-phenylalanine without adding L-tyrosine and L-tryptophan, revertant strain MWEC 101 was isolated from MWEC 83. Further various analogues and valine resistant mutants were isolated from MWEC 101. MWEC 101-5 was the most excellent strain that produced 17.9g/l of L-phenylalanine after having been cultivated for 54 hours in 15% glucose medium. It was disclosed that activities of rate-limiting enzymes including chorismate mutase and prephenate dehydratase in MWEC 101-5 were desensitized to 2mM L-phenylalanine in the enzyme reaction mixture and that activities level of 3-deoxy-D-arabino-heptulosonic acid-7-phosphate synthase and prephenate dehydratase were increased more than 20 times over those of the parental strain.

L-Phenylalanine을 대량생산하는 균주를 얻기 위하여 Escherichia coli K-12로부터 여러대사조절 변이주를 분리하였다. MWEC 83은 L-phenylalanine을 7.4 g/l 생산하는 tyrosine, tryptophan 이중 영양요구성 변이주이다. Tyrosine과 tryptop phan의 첨가없이 L-phenylalanine을 생산하기 위하여 MWEC 83으로부터 복기변이주 MWEC 101을 분리하였다. 또한 MWEC 101 균주로부터 여러 analog와 valine 내성주를 분리하였다. MWEC 101-5는 포도당 15%로 배양 54시간에 17.9 g/l의 L-phenylalanine을 생산하는 최고 우량균주이다. MWEC 101-5의 chorismate mutase와 prephenate dehydratase 효소환성은, 효소반응 혼합액 속에 2mM phenylalanine에 대하여 효소활성이 저해되지 않았다.