Increased expression of recombinant cholesterol oxidase in Escherichia coli by optimization of culture condition using response surface methodology

Aim. The FAD-containing enzyme, cholesterol oxidase
(EC 1.1.3.6) is an enzyme that catalyses sequential
reactions which convert cholesterol (5-cholesten-3-bol)
to 4-cholesten-3-one with concomitant reduction
of oxygen to hydrogen peroxide. In fact, this enzyme
catalyzes two reactions in one active site: oxidation
and isomerization. Cholesterol oxidase is an industrially
and commercially important enzyme.
Methods. Response surface methodology that uses
quantitative data from appropriate experiments was
applied to optimize the culture conditions for recombinant
cholesterol oxidase production in Escherichia
coli (E. coli). Parameters considered were concentrations
of IPTG, induction time, fermentation temperature
and incubation period. Design of optimal experimental
conditions was performed by four-factor, three
levels Box-Behnken model which yielded improved
cholesterol oxidase production.
Results. Under optimal condition, productivity of cholesterol
oxidase increased approximately 2-fold as
compared to un-optimized medium.
Conclusion. These findings demonstrate that response
surface methodology could efficiently be applied for
optimization of recombinant cholesterol oxidase production
in E. coli as the experimental data for productivity
of cholesterol oxidase had a good correlation
with predicted values