earticle

영어

Galactooligosacchride (GOS) as a prebiotic is known to be beneficial to the growth of human intestinal microbial flora, and thereby led eventually to control the human diseases. Typically GOS is synthesized by β-galactosidase (β-gal)-catalyzed enzymatic reaction on lactose. During this reaction (transgalactosylation), galactose moiety is known to be transferred to hydroxyl group of lactose, and thereby GOS is synthesized.
There have been lots of reports related to GOS production by β-galactosidase and immobilized β -galactosidase. Recently, in order to increase the productivity of GOS, various reactor systems and operational strategies have been studied. In our previous studies, it was demonstrated that active Escherichia coli (E.coli) β-gal inclusion bodies (IBs) were produced by the addition of a repressor (α-methyl D-glucospyranoside) or an inducer analog (D-fucose) after induction of the araBAD promoter system in E.coli. Inaddition, we have operated successfully a packed-bed reactor for hydrolysis of o-nitrophenyl-ß-D-galactoside using immobilized β-gal IBs-containing E.coli cells. Previously, it has been reported that enzyme IBs in E.coli expression system were expressed as biologically active IBs. However, there have been little numbers of report that have explored an enzyme reactor using active IBs. The aim of this study is to investigate whether β-gal IBs-containing E.coli cell can synthesize GOS by transgalactosylation reaction, and, in addition, to explore the optimal condition of GOS synthesis by this β-gal IBs-containing E.coli cell. Interestingly, this study is the first trial for GOS synthesis by β-gal IBs. Because, if we can use active β-IBs as biocalayst, β-IB utilization will be more convenient and economic in enzymatic GOS synthesis, active β-gal IBs might be applied to the enzymatic transgalactosylation reaction without any purification steps. That is, a whole E.coli cells containing active β-gal IBs will be able to be directly used for GOS synthesis.