title: L-Ribulose production by an Escherichia coli harboring L-arabinose isomerase from Bacillus licheniformis.
abstract: Recombinant Escherichia coli harboring the L: -arabinose isomerase (BLAI) from Bacillus licheniformis was used as a biocatalyst to produce L: -ribulose in the presence of borate. Effects of substrate concentration, the borate to L: -arabinose ratio, pH, and temperature on the conversion of L: -arabinose to L: -ribulose were investigated. L: -Ribulose production was efficient when pH was higher than 9 and temperature was higher than 50 degrees C. Borate addition to the reaction mixture was essential for high conversion of L: -arabinose to L: -ribulose as it resulted in an equilibrium shift in favor of the product. Under the optimal conditions determined by response surface methodology, the E. coli harboring BLAI produced 375 g l(-1) L-ribulose from 500 g l(-1) L: -arabinose at a reaction time of 60 min, corresponding to a conversion yield of 75% and productivity of 375 g l(-1) h(-1). When the resting recombinant E. coli cells were recycled, 85% of the yield was obtained even after seven cycles of reuse. The productivity and final concentration of L: -ribulose obtained in the present study were the highest yet reported.
authors.affiliation: Department of Chemical Engineering, Konkuk University, Seoul, Korea.
authors.forename: Ye-Wang
authors.initials: YW
authors.lastname: Zhang
authors.forename: Marimuthu
authors.initials: M
authors.lastname: Jeya
authors.forename: Jung-Kul
authors.initials: JK
authors.lastname: Lee
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D010429:Pentoses / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D010429:Pentoses; C100182:ribulose; D019747:Aldose-Ketose Isomerases; C019715:L-arabinose isomerase