L-isoleucine-producing bacterium and method for preparing L- isoleucine through fermentation

摘要

An L-isoleucine-producing bacterium belonging to the genus Escherichia which carries a thrABC operon which comprises a thrA gene coding for aspartokinase I-homoserine dehydrogenase I substantially released from the inhibition by L-threonine and an ilvGMEDA operon which comprises an ilvA gene coding for threonine deaminase substantially released from the inhibition by L-isoleucine and whose region required for attenuation is removed; and an L-isoleucine-producing bacterium belonging to the genus Escherichia carrying the thrABC operon, an lysC gene coding for aspartokinase III substantially released from the inhibition by L-lysine, and the ilvGMEDA operon. The bacteria permit biosynthesis of a sufficient amount of L-isoleucine.