Abstract

In order to produce phenylalanine without tyrosine co-production, we constructed various temperature-controllable expression vectors by insertion of lower expression of the tyrA gene into the plasmid pSY130-14. And tyrosine revertant to cultivate without addition of tyrosine, was selected from Escherichia coli strain AT2471[tyrA , thi ] by spontaneous mutation. The strain AT2471 harbouring plasmid pSY146A and the tyrosine revertant 5 harbouring plasmid pSY111-14 produced 12 g/l and 15 g/l of phenylalanine respectively in a 2.5 l jar fermenter at a constant temperature of $39^{\circ}C$ after 55 hours cultivation.

Phenylalanine 생산시 tyrosine이 부생되지 않도록 tyrA유전자 발현이 낮은 여러 가지 온도조절형 plasmid를 제작하였으며, phenylalanine 생산균주인 대장균 AT2471$[tyrA^-,\;thi^-]$은 tyrosine 영양요구 변이균주이므로 생산배지에 tyro-sine 첨가없이 phenylalanine을 생산할 수 있도록 하기 위하여 tyrosine 복귀변이균주를 분리하여 phenylalanine 생산을 검토하였다. 2.5 l jar fermenter를 사용하여 tyrosine 첨가없이 phenylalanine 생산을 검토하여 대장균 AT2471/pSY146A, 대장균 AT2471 tyrosine 복귀변이균주 5/pSY111-14를 $39^{\circ}C$에서 55시간 배양한 결과 각각 12 g/l, 15 g/l를 생산하였다.

Keywords

• molecular breeding;
• phenylalanine production;
• temperature-controllable vector;
• E. coli