Bioconversion of D-galactose into D-tagatose by expression of L-arabinose isomerase.
D-Tagatose is a potential bulking agent in food as a non-calorific sweetener. To produce D-tagatose from cheaper resources, plasmids harbouring the L-arabinose isomerase gene (araA) from Escherichia coli, Bacillus subtilis and Salmonella typhimurium were constructed because L-arabinose isomerase was suggested previously as an enzyme that mediates the bioconversion of galactose into tagatose as well as that of arabinose to ribulose. The constructed plasmids were named pTC101, pTC105 and pTC106, containing araA from E. coli, B. subtilis and S. typhimurium respectively. In the cultures of recombinant E. coli with pTC101, pTC105 and pTC106, tagatose was produced from galactose in 9.9, 7.1 and 6.9% yields respectively. The enzyme extract of E. coli with the plasmid pTC101 also converted galactose into tagatose with a 96.4% yield.
Roh
H J
HJ
R&D Center, Tong Yang Confectionery Co., 30-10 Munbai-dong, Yongsan-ku, Seoul 140-715, Korea.
Kim
P
P
Park
Y C
YC
Choi
J H
JH
D019747:Aldose-Ketose Isomerases / Q000235:genetics* / Q000378:metabolism*; D001412:Bacillus subtilis / Q000235:genetics; D001709:Biotechnology / Q000379:methods; D004926:Escherichia coli / Q000235:genetics*; D005690:Galactose / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005818:Genetic Engineering / Q000379:methods*; D006601:Hexoses / Q000096:biosynthesis*; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics; D014169:Transformation, Bacterial / Q000235:genetics
D006601:Hexoses; D011994:Recombinant Proteins; D019747:Aldose-Ketose Isomerases; C019715:L-arabinose isomerase; C030192:tagatose; D005690:Galactose