Patent ID: 7118894

Claim:
A process for the production of L-lysine comprising culturing a raffinate-resistant bacterial strain B in a bacterial fermentation medium containing at least about 2% raffinate based on ammonium sulfate content, wherein said raffinate is the broth effluent waste stream product generated during the ion-exchange chromatographic purification of L-lysine, wherein said raffinate-resistant bacterial strain B is obtained by: (i) selecting a parental bacterial strain A that produces L-lysine; (ii) subjecting said parental bacterial strain A to mutagenesis; (iii) culturing the mutagenized parental bacterial strain A in a bacterial selection medium containing at least about 1% raffinate based on ammonium sulfate content, wherein said raffinate is the broth effluent waste stream product generated during the ion-exchange chromatographic purification of L-lysine; (iv) selecting said raffinate-resistant bacterial strain B from the bacterial selection medium containing said mutagenized parental bacterial strain A of part (iii), wherein said raffinate-resistant bacterial strain B is able to grow to a higher optical density at a wavelength of 660 nm than said parental bacterial strain A; (v) culturing said raffinate-resistant bacterial strain B in a bacterial fermentation medium containing at least about 2% raffinate based on ammonium sulfate content, wherein said raffinate is the broth effluent waste stream product generated during the ion-exchange chromatographic purification of L-lysine, wherein said bacterial strain B produces a higher amount of L-lysine compared to said parental bacterial strain A; and (vi) recovering the L-lysine from said bacterial fermentation medium.