title: Screening and immobilization Burkholderia sp. GXU56 lipase for enantioselective resolution of (R,S)-methyl mandelate.
abstract: Microorganisms producing lipase were isolated from soil and sewage samples and screened for enantioselective resolution of (R,S)-methyl mandelate to (R)-mandelic acid. A strain designated as GXU56 was obtained and identified as Burkholderia sp. Preparing immobilized GXU56 lipase by simple adsorption on octyl sepharose CL-4B, the optimum temperature was shifted from 40 degrees C (free lipase) to 50 degrees C (immobilized lipase), and the optimum pH was shifted from 8.0 (free lipase) to 7.2 (immobilized lipase). The immobilized enzyme displayed excellent stability in the pH range of 5.0-8.0, at the temperatures below 50 degrees C and in organic solvents compared with free enzyme. Enantioselectivity ratio for (R)-mandelic acid (E) was dramatically improved from 29.2 to more than 300 by applying immobilized lipase in the resolution of (R,S)-methyl mandelate. After five cycles of use of immobilized lipase, conversion and enantiomeric excess of (R)-mandelic acid were 34.5% and 98.5%, respectively, with enantioselectivity ratio for (R)-mandelic acid (E) of 230. Thus, octyl-sepharose-immobilized GXU56 lipase can be used as a bio-resolution reagent for producing (R)-mandelic acid.
authors: College of Life Science and Technology, Guangxi University, Guangxi, 530005, People's Republic of China.
authors: Han-Ning
authors: HN
authors: Wei
authors: Bo
authors: B
authors: Wu
mesh_terms: D019117:Burkholderia / Q000201:enzymology*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008049:Lipase / Q000378:metabolism*; D008333:Mandelic Acids / Q000737:chemistry* / Q000378:metabolism; D012685:Sepharose / Q000031:analogs & derivatives; D012997:Solvents; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D004800:Enzymes, Immobilized; D008333:Mandelic Acids; D012997:Solvents; C414090:methyl mandelate; C027176:octyl-sepharose CL-4B; D012685:Sepharose; D008049:Lipase; C037938:mandelic acid