Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing alpha or beta amino acid or substituted amino acid...
Patent
1997-06-09
1998-10-27
Huff, Sheela
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing alpha or beta amino acid or substituted amino acid...
530350, 435 711, 435 29, 435183, 4352528, 536 231, 536 232, C12P 1308, C07H 2100, C07H 2102, C07H 2104
Patent
active
058276980
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a novel lysine decarboxylase gene of Escherichia coli relevant to decomposition of L-lysine, a microorganism belonging to the genus Escherichia with restrained expression of the gene and/or another lysine decarboxylase gene known as cadA gene, and a method of producing L-lysine by using the microorganism. Recently, the demand of L-lysine as a feed additive actively increases.
BACKGROUND ART
Lysine decarboxylase, which catalyzes a reaction to produce cadaverine by decarboxylation of L-lysine, is known as an L-lysine-decomposing enzyme of Escherichia coli. A nucleotide sequence of its gene called cadA, and an amino acid sequence encoded by the gene have been already reported (Meng, S. and Bennett, G. N. , J. Bacteriol., 174, 2659 (1992)). There are two reports for lysine decarboxylase encoded by a gene other than cadA of Escherichia coli, which describe that faint activity was detected in a mutant strain of Escherichia coli (Goldemberg, S. H. , J. Bacteriol., 141, 1428 (1980); Wertheimer, S. J. and Leifer, Z., Biochem. Biophys. Res. Commun., 114, 882 (1983)). However, it was reported for this activity by Goldemberg, S. H. that the enzyme activity decreased in a degree of about 30% after a heat treatment at 60.degree. C. for 4 minutes, while it was reported by Wertheimer, S. J. et al that no such phenomenon was observed. Accordingly, the presence of the second lysine decarboxylase is indefinite.
On the other hand, L-lysine is produced by known methods for using Escherichia coli, including a method comprising cultivating a mutant strain resistant to lysine analog or a recombinant strain harboring a vector with incorporated deoxyribonucleic acid which carries genetic information relevant to L-lysine biosynthesis (Japanese Patent Laid-open No. 56-18596). However, there is no report at all for L-lysine production by using a microorganism belonging to the genus Escherichia with restrained expression of the lysine decarboxylase gene.
DISCLOSURE OF THE INVENTION
An object of the present invention is to obtain a novel lysine decarboxylase gene of Escherichia coli, create an L-lysine-producing microorganism belonging to the genus Escherichia with restrained expression of the gene and/or the cadA gene, and provide a method of producing L-lysine by cultivating the microorganism belonging to the genus Escherichia. When the present inventors created an Escherichia coli strain in which the cadA gene as a known lysine decarboxylase gene was destroyed, it was found that cadaverine as a decomposition product of L-lysine by lysine decarboxylase was still produced in this microbial strain. Thus the present inventors assumed that a novel lysine decarboxylase gene should be present in Escherichia coli, and it might greatly affect fermentative production of L-lysine by using a microorganism belonging to the genus Escherichia. As a result of trials to achieve cloning of the gene, the present inventors succeeded in obtaining a novel lysine decarboxylase gene different from the cadA gene. It was also found that the L-lysine-decomposing activity was remarkably decreased or disappeared, and the L-lysine productivity was significantly improved by restraining expression of this gene, and restraining expression of the cadA gene in an L-lysine-producing microorganism of Escherichia coli. Thus the present invention was completed.
Namely, the present invention provides a novel gene which codes for lysine decarboxylase originating from Escherichia coli. This gene has been designated as "ldc" gene.
In another aspect, the present invention provides a microorganism belonging to the genus Escherichia having L-lysine productivity with decreased or disappeared lysine decarboxylase activity in cells.
In still another aspect, the present invention provides a method of producing L-lysine comprising the steps of cultivating, in a liquid medium, the microorganism belonging to the genus Escherichia described above to allow L-lysine to be produced and accumulated in a culture liquid, and collecting i
REFERENCES:
CA 111:209849. 1989.
CA 1056:36506. 1986.
Meng et al., J. Bacteriology vol. 174 p. 2659. 1992.
Kikuchi Yoshimi
Kojima Hiroyuki
Suzuki Tomoko
Ajinomoto Co. Inc.
Huff Sheela
LandOfFree
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