106.
Epoxide hydrolases (EHs) of fungal origin have the ability to catalyze the enantioselective hydrolysis of epoxides to their
corresponding diols. However, wild type fungal EHs are limited in substrate range and enantioselectivity. Additionally, the
production of fungal epoxide hydrolase (EH) by wild-type strains is typically very low. In the present study, the EH-encoding
gene from
Rhodotorula araucariae was functionally expressed in
Yarrowia lipolytica, under the control of a growth phase inducible
hp4d promoter, in a multi-copy expression cassette. The transformation experiments yielded a positive transformant, with a final
EH activity of 220 U/g dw in shake-flask cultures. Evaluation of this transformant in batch fermentations resulted in ~ 7-fold
improvement in EH activity over the flask scale. Different constant specific feed rates were tested in fed-batch fermentations,
resulting in an EH activity of 1,750 U/g dw at a specific feed rate of ~ 0.1 g/g/h, in comparison to enzyme production levels
of 0.3 U/g dw for the wild type
R. araucariae and 52 U/g dw for an
Escherichia coli recombinant strain expressing the same gene. The expression of EH in
Y. lipolytica using a multi-copy cassette demonstrates potential for commercial application.
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