TH43977A - Newly discovered genes and methods for L-amino acid production. - Google Patents

Abstract

DC60 (07/03/43) Bacteria capable of producing amino acids and in which the rhtC gene transcribing the L-threonine-tolerant protein is dominant, and in which the rhtB gene transcribing the L-homoserine-tolerant protein is further dominant, are cultured in a medium to produce and accumulate amino acids in the medium, and the amino acids are then removed from the medium.

Claims (10)

1. Bacteria of the Escherichia genus, where the L-threonine tolerance of the said bacteria is enhanced by the exponential function of the protein as defined in (A) or (B) below in the said bacterial cells; (A) a protein consisting of the amino acid sequence shown in sequence No. 4 in the sequence list; or (B) a protein consisting of an amino acid sequence incorporating the deletion, substitution, addition or addition of one or more amino acids in the amino acid sequence shown in sequence No. 4 in the sequence list, and which functions to make the bacteria L-threonine tolerant. 2. Bacteria pursuant to claim 1, whereby the L-homoserine tolerance of the said bacteria is further exacerbated by the exacerbation of the function of the protein as defined in (C) or (D) below in the said bacterial cells; (C) a protein consisting of the amino acid sequence shown in sequence No. 2 in the sequence list; or (D) a protein consisting of the amino acid sequence incorporating the deletion, substitution, addition or addition of one or more amino acids in the amino acid sequence shown in sequence No. 2 in the sequence list and which functions to make the bacteria L-homoserine-tolerant. 3. Bacteria according to claim 1 or 2 where the function described of the protein as defined in (A) or (B) is enhanced by the transfection of the bacteria with DNA transcribed for the protein as defined in (A) or (B). 4. Bacteria according to claim 2, where the function described of the protein as defined in (C) or (D) is enhanced by the transmutation of the bacteria described with DNA that encodes the protein as defined in (C) or (D). 5. An amino acid production method consisting of the following steps: culturing bacteria as defined in one of Reputations 1 through 4, which are capable of producing amino acids in a culture medium, to produce and accumulate amino acids in the medium, and removing the amino acids from the medium. 6. Method according to claim 5, where the amino acids mentioned are selected from a group consisting of L-homoserin, L-threonine, and branched-chain amino acids. 7. Method according to claim 6, where the branched-chain amino acid referred to is L-valine or L-leucine. 8. DNA that transcribes the protein in (A) or (B) of the following: (A) a protein whose amino acid sequence is: 4; (B) a protein whose amino acid sequence is: 4 that includes a substitution, deletion, addition, addition or reversal of one or more amino acids and has the function of making the bacterial protein resistant L-threonine. 9. DNA of claim 8, which is DNA as defined in (a) or (b) below: (a) DNA containing the nucleotide sequence of nucleotides 187 to 804 in sequence: 3; (b) DNA which can be recombined with the nucleotide sequence of nucleotides 187 to 804 in sequence: 3, or a test prepared from the nucleotide sequence under strict conditions, and decodes a protein that makes bacteria resistant to L-threonine. 10. DNA of claim 9, where the strict condition is the condition in which washing is performed at 60°C and the salt concentration is in accordance with 1xSSC and 0.1%SDS.