Abstract

 A L-valine hyper-producer Brevibacterium flavum XQ-6 (Leu^l, Ile^l, AHV^r, α-AB^hr, 2-TA^hr) was obtained, which could be resistant to high concentration of α-amino-butyric acid (α-AB) and 2-thiazolealanaine (2-TA). The metabolic network of XQ-6 was regulated with the addition of amino acids, organic acids, vitamins, bases and other organic things. The carbon flux was directed to L-valine by manipulating the specific activity of α-ketoglutarate dehydrogenase complex (KGDH). With a combinational regulation strategy, the highest L-valine concentration of 67.7 g/L was achieved.

Key words: L-valine, Brevibacterium flavum, HPLC, metabolic analysis. 

Abbreviation

EMP, Embden-Meyerhof-Parnas pathway; HPLC, high performance liquid chromatogratography; NTG, N-methyl-N’-nitro-soguanidine;HMP, hexose monophophate pathway; KGDH, α-ketoglutarate dehydrogenase complex; α-AB, α-amino-butyric acid; DES, diethylstilboestrol; 2-TA, 2-thiazolealanaine.