title: Efficient synthesis of enantiomeric ethyl lactate by Candida antarctica lipase B (CALB)-displaying yeasts.
abstract: The whole-cell biocatalyst displaying Candida antarctica lipase B (CALB) on the yeast cell surface with alpha-agglutinin as the anchor protein was easy to handle and possessed high stability. The lyophilized CALB-displaying yeasts showed their original hydrolytic activity and were applied to an ester synthesis using ethanol and L: -lactic acid as substrates. In water-saturated heptane, CALB-displaying yeasts catalyzed ethyl lactate synthesis. The synthesis efficiency increased depending on temperature and reached approximately 74% at 50 degrees C. The amount of L: -ethyl lactate increased gradually. L: -Ethyl lactate synthesis stopped at 200 h and restarted after adding of L: -lactic acid at 253 h. It indicated that CALB-displaying yeasts retained their synthetic activity under such reaction conditions. In addition, CALB-displaying yeasts were able to recognize L: -lactic acid and D: -lactic acid as substrates. L: -Ethyl lactate was prepared from L: -lactic acid and D: -ethyl lactate was prepared from D: -lactic acid using the same CALB-displaying whole-cell biocatalyst. These findings suggest that CALB-displaying yeasts can supply the enantiomeric lactic esters for preparation of useful and improved biopolymers of lactic acid.
authors.affiliation: Kyoto University, Sakyo-ku, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Inaba
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Maekawa
authors.forename: Hironobu
authors.initials: H
authors.lastname: Morisaka
authors.forename: Kouichi
authors.initials: K
authors.lastname: Kuroda
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Ueda
mesh_terms: D055162:Biocatalysis; D002175:Candida / Q000201:enzymology; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D007773:Lactates / Q000737:chemistry / Q000378:metabolism*; D019344:Lactic Acid / Q000737:chemistry / Q000378:metabolism; D008049:Lipase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D005656:Fungal Proteins; D007773:Lactates; D019344:Lactic Acid; D008049:Lipase; C431349:lipase B, Candida antarctica; C015866:ethyl lactate