Abstract: A method for producing an L-amino acid is described, for example, L-phenylalanine and L-histidine, by fermentation using a bacterium of the Enterobacteriaceae family, wherein the bacterium has been modified by attaching a DNA fragment able to be transcribed encoding the peptide represented in SEQ ID NO: 2, or a variant thereof, particularly a portion of the ssrA gene, to the 3?-end of gene encoding for the bacterial enzyme, which influences on the L-amino acid biosynthesis, such as chorismate mutase/prephenate dehydrogenase or phosphoglucose isomerase.

Abstract: A method for producing an L-amino acid is described, for example, L-phenylalanine and L-histidine, by fermentation using a bacterium of the Enterobacteriaceae family, wherein the bacterium has been modified by attaching a DNA fragment able to be transcribed encoding the peptide represented in SEQ ID NO: 2, or a variant thereof, particularly a portion of the ssrA gene, to the 3?-end of gene encoding for the bacterial enzyme, which influences on the L-amino acid biosynthesis, such as chorismate mutase/prephenate dehydrogenase or phosphoglucose isomerase.

Abstract: A method for producing an L-amino acid is described, for example, L-phenylalanine and L-histidine, by fermentation using a bacterium of the Enterobacteriaceae family, wherein the bacterium has been modified by attaching a DNA fragment able to be transcribed encoding the peptide represented in SEQ ID NO: 2, or a variant thereof, particularly a portion of the ssrA gene, to the 3?-end of gene encoding for the bacterial enzyme, which influences on the L-amino acid biosynthesis, such as chorismate mutase/prephenate dehydrogenase or phosphoglucose isomerase.

Abstract: The present invention relates to a mutant bacterial PRPP synthetase which is resistant to feedback by purine nucleotides, and a method for producing L-histidine using the bacterium of the Enterobacteriaceae family wherein the L-amino acid productivity of said bacterium is enhanced by use of the PRPP synthetase which is resistant to feedback by purine nucleotides, coded by the mutant prsA gene.

Abstract: A method is provided for producing L-histidine using bacterium of the Enterobacteriaceae family wherein the L-amino acid productivity of said bacterium is enhanced by enhancing an activity of the AICAR transformylase-IMP cyclohydrolase encoded by the purH gene.

Abstract: The present invention relates to a mutant bacterial PRPP synthetase which is resistant to feedback by purine nucleotides, and a method for producing L-histidine using the bacterium of the Enterobacteriaceae family wherein the L-amino acid productivity of said bacterium is enhanced by use of the PRPP synthetase which is resistant to feedback by purine nucleotides, coded by the mutant prsA gene.

Abstract: A method for producing an L-amino acid is described, for example, L-phenylalanine and L-histidine, by fermentation using a bacterium of the Enterobacteriaceae family, wherein the bacterium has been modified by attaching a DNA fragment able to be transcribed encoding the peptide represented in SEQ ID NO: 2, or a variant thereof, particularly a portion of the ssrA gene, to the 3?-end of gene encoding for the bacterial enzyme, which influences on the L-amino acid biosynthesis, such as chorismate mutase/prephenate dehydrogenase or phosphoglucose isomerase.

Abstract: A method for constructing microorganism strains which produce amino acids comprising: combining in one bacterial genome (a) a mutation affecting the aminoacyl-tRNA synthetase corresponding to the selected amino acid, conferring cells auxotrophy which cannot be fully suppressed by addition of usual concentration this amino acid into the culture medium and (b) a mutation which destroys the negative regulation of selected amino acid biosynthesis to yield a strain capable of increased production of the selected amino acid.Strains producing isoleucine and valine.Methods to produce isoleucine and valine by culturing those strains.