title: Efficient synthesis of octyl-β-d-galactopyranoside by Bacillus spore-displayed β-galactosidase using an amphiphilic 1,2-dimethoxyethane co-solvent.
abstract: For enzymatic synthesis of octyl-β-d-galactopyranoside (octyl-gal) from lactose and n-octanol, Escherichia coli β-galactosidase (β-Gal) was expressed and displayed on the surfaces of Bacillus subtilis spores. The spore-displayed β-Gal was found to be stable when an amphiphilic 1,2-dimethoxyethane (DME) was used as a co-solvent; the transgalactosylation efficiency and octyl-gal conversion were optimal at 50% (v/v) DME. In addition, the product was maximally obtained from 100mM lactose in a phosphate buffer/n-octanol/DME (25/25/50, v/v) mixture. By increasing the agitation speed and the amount of spores displaying β-Gal, a yield of 33.7 mM octyl-gal was obtained over 24h in a batch mode, which is much higher than in other octyl-gal bioconversion processes, such as those involving lipid-coating, reverse micelles, or whole cells. On the other hand, intermittent addition of spore-displayed β-Gal and/or lactose in the reaction medium had no effect on the octyl-gal yield. The synthesized octyl-gal was hydrolyzed by the spore-displayed β-Gal, and a high concentration of octyl-gal competitively inhibited the enzymes (K(i) value of 10.8mM). In summary, we demonstrate that octyl-gal synthesis by spore-displayed β-Gal in non-aqueous medium can be significantly improved with the use of DME as a co-solvent.
authors: Industrial Biotechnology and Bioenergy Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 111 Gwahangno, Yuseong-gu, Daejeon 305-806, Republic of Korea.
authors: Jungdon
authors: J
authors: Bae
authors: Eun Hwa
authors: EH
authors: Choi
authors: Jae-Gu
authors: JG
authors: Pan
mesh_terms: D020003:1-Octanol / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D001709:Biotechnology / Q000379:methods*; D004795:Enzyme Stability; D005019:Ethyl Ethers; D005697:Galactosides / Q000096:biosynthesis*; D006031:Glycosylation; D006868:Hydrolysis; D007785:Lactose / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012997:Solvents; D013171:Spores, Bacterial / Q000201:enzymology*; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D005019:Ethyl Ethers; D005697:Galactosides; D011994:Recombinant Proteins; D012997:Solvents; C087303:octyl galactopyranoside; D001616:beta-Galactosidase; C024683:1,2-dimethoxyethane; D007785:Lactose; D020003:1-Octanol