Efficient synthesis of enantiomeric ethyl lactate by <Emphasis Type="Italic">Candida antarctica</Emphasis> lipase B (CALB)-displaying yeasts |
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Authors: | Chiaki Inaba Kenjiro Maekawa Hironobu Morisaka Kouichi Kuroda Mitsuyoshi Ueda |
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Affiliation: | (1) Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan |
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Abstract: | The whole-cell biocatalyst displaying Candida antarctica lipase B (CALB) on the yeast cell surface with α-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°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. |
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Keywords: | Candida antarctica lipase B (CALB) Whole-cell biocatalyst Ethyl lactate Biodegradable plastics Enantiomer synthesis |
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