FACTORS IMPROVING L-THREONINE PRODUCTION BY A 3 L-THREONINE BIOSYNTHETIC GENES AMPLIFIED RECOMBINANT STRAIN OF BREVIBACTERIUM-LACTOFERMENTUM

When a Brevibacterium lactofermentum L-threonine producer that accumul ated L-lysine as well, was transformed with a recombinant plasmid carr ying the indigenous hom, thrB, and thrC genes, delayed growth and plas mid instability were observed. Addition of organic nutrients, vitamins (thiamine.HCl and d-biotin), and NaCl under the optimal culture condi tions solved these problems and further increased threonine production in a small jar fermentor.