Acquisition of a sucrose utilization system in Escherichia coli K-12 derivatives and its application to industry.
An Escherichia coli strain, B-62, that was isolated from a clinical source and was epidemiologically unrelated to E. coli K-12 was the source of chromosomal DNA for a sucrose utilization system (Scr+) in the construction of a plasmid, pST621. The cloned insert of a gene encoding Scr+ in pST621 conferred a sucrose-positive phenotype onto transformed cells of E. coli K-12 derivatives. Sucrase activity of the transformants was as high as that which would correspond to a "gene dosage effect" of a vector plasmid pBR322, whereas the transformants' sucrose uptake activity was always lower than that of E. coli B-62. A region within an XhoI-SacI fragment (3.2 kb) of pBR322-glyA was replaced in the construction of another plasmid, pST5R7, by a fragment (about 2.6 kb) of pST622 containing the gene encoding Scr+. A genetically stable Scr+ derivative of E. coli K-12 was obtained by introducing the gene encoding Scr+ onto E. coli chromosome via homologous recombination between pST5R7 and the chromosome and subsequent plasmid segregation. The use of low-copy-number plasmid RP4 as a cloning vector was also effective for enhancing the stability of Scr+. Tryptophan producers E. coli SGIII1032S, in which the gene encoding Scr+ was cloned onto the chromosome, and E. coli SGIII1032, which carried Scr+ plasmid RP4.5R7, produced from 6% sucrose in shake flasks (33 degrees C, 96 h) 2.3 and 5.7 g of tryptophan per liter, respectively.
Tsunekawa
H
H
Mercian Co., Central Research Laboratories, Kanagawa, Japan.
Azuma
S
S
Okabe
M
M
Okamoto
R
R
Aiba
S
S
D001693:Biological Transport, Active / Q000235:genetics; D001709:Biotechnology; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D005818:Genetic Engineering; D005822:Genetic Vectors; D010957:Plasmids; D013393:Sucrase / Q000235:genetics / Q000378:metabolism; D013395:Sucrose / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic; D014364:Tryptophan / Q000096:biosynthesis
D013395:Sucrose; D014364:Tryptophan; D013393:Sucrase