Screening and Immobilization Burkholderia sp. GXU56 Lipase for Enantioselective Resolution of (R,S)-Methyl Mandelate

• DOI: 10.1007/s12010-007-8125-8
• Publication Date: 2008-01-25T14:55:28Z
• Authors: Han-Ning Wei; Bo Wu
• Keywords: 0106 biological sciences; Burkholderia; Hydrolysis; Sepharose; Temperature; Stereoisomerism; Lipase; Hydrogen-Ion Concentration; Enzymes, Immobilized; 01 natural sciences; 6. Clean water; Enzyme Stability; Solvents; Mandelic Acids

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.