Construction of Lactobacillus plantarum strain with enhanced L-lysine yield.
OBJECTIVE
To enhance L-lysine secretion in Lactobacillus plantarum.


RESULTS
An S-2-aminoethyl-L-cystein (AEC)-resistant mutant of L. plantarum was isolated, and it produced L-lysine at considerably higher level than the parent strain. Aspartokinase in the mutant has been desensitized to feedback inhibition by L-lysine. The nucleotide sequence analysis of thrA2 that codes for aspartokinase in the mutant predicted a substitution of glutamine to histidine at position 421. L-Lysine-insensitive aspartokinase, together with aspartate semialdehyde dehydrogenase, dihydrodipicolinate synthase, and dihydrodipicolinate reductase genes, was cloned from L. plantarum DNA to a shuttle vector, pRN14, and the genes were then transformed individually into the AEC-resistant mutant and the parent strain. The overexpression of the genes led to the increase in the activity of enzymes they encode in vitro. However, only the strain overexpressing aspartokinase or dihydrodipicolinate synthase produced more L-lysine.


CONCLUSIONS
The desensitization of aspartokinase to L-lysine in L. plantarum led to the overproduction of L-lysine. The overexpression of L-lysine-insensitive aspartokinase or dihydrodipicolinate synthase enhanced L-lysine secretion in L. plantarum.


CONCLUSIONS
The use of the L-lysine-overproducing strain of L. plantarum in food or feed fermentation may increase the L-lysine content of fermented products.
Cahyanto
M N
MN
The International Center for Biotechnology, Osaka University, Osaka, Japan.
Kawasaki
H
H
Nagashio
M
M
Fujiyama
K
K
Seki
T
T
D000595:Amino Acid Sequence; D001222:Aspartate Kinase / Q000235:genetics; D001223:Aspartate-Semialdehyde Dehydrogenase / Q000235:genetics; D001483:Base Sequence; D003545:Cysteine / Q000031:analogs & derivatives / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D050746:Dihydrodipicolinate Reductase / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D006836:Hydro-Lyases / Q000235:genetics; D048191:Lactiplantibacillus plantarum / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D008239:Lysine / Q000096:biosynthesis*; D009154:Mutation; D011500:Protein Synthesis Inhibitors; D011995:Recombination, Genetic / Q000235:genetics
D004269:DNA, Bacterial; D011500:Protein Synthesis Inhibitors; C000204:S-2-aminoethyl cysteine; D050746:Dihydrodipicolinate Reductase; D001223:Aspartate-Semialdehyde Dehydrogenase; D001222:Aspartate Kinase; D006836:Hydro-Lyases; C020040:4-hydroxy-tetrahydrodipicolinate synthase; D008239:Lysine; D003545:Cysteine