Patent ID: 7220571
Filing Date: 2007-05-22
Classification: C12N,C12P,C12R

Abstract:
1. A process for producing a mutagenized threonine raffinate-resistant Escherichia coli strain that overproduces L-threonine compared to an unmodified E. coli strain, said process comprising: (a) inserting into the chromosome of an (b) performing at least one cycle of mutagenesis on the parent strain; (c) screening the mutagenized parent cells to identify mutagenized parent strains which produce between about 95 and about 150 g/L of threonine by about 48 hours of growth in culture; (d) culturing said mutagenized parent strains in a medium containing at least 0.2% threonine raffinate based on ammonium sulfate content wherein said threonine raffinate is the broth effluent waste stream product generated during ion-exchange chromatographic purification of L-threonine; and (e) selecting at least one threonine raffinate-resistant mutagenized produces between about 95 and about 150 g/L of L-threonine by about 48 hours of growth in culture.