On the whole-cell cell saccharomyces cerevisiae biotransformation of ketoisophorone at different substrate concentrations
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Date
2018-06
Authors
Illya Syafiqah Mohd Razif
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Abstract
Baker’s yeast type II has been utilized in this study as a biocatalyst to
investigate the reduction of 2, 6, 6-trimethylcyclohex--2-ENE-1,4-Dione
(ketoisophorone) into a useful chiral intermediates as well as for its valuable product
that is (4R,6R) -4-hydroxy-2,6,6-trimethylcyclohexanone or in short (4R, 6R) -actinol.
Five different substrate of ketoisophorone has been introduced at different culture in
order to investigate the effect of the cofactor regeneration and the time courses of
ketoisophorone to produce corresponding intermediates of 2,6,6-
trimethylcyclohexane-1,4-dione [(6R)-levodione] and 4-hydroxy-2,6,6-
trimethylcyclohex-2-ene-1-one [(4S)-phorenol] and the main product (R)-hydroxy 2,2,6-trimethylcycloheanone [(4R,6R)-actinol] on the whole- cell Saccharomyces
cerevisiae. The cofactor availability and stability has been investigated by using
ultraviolet-visible and it was found that at 2.0 g/L of substrate concentration the
cofactor availability is the lowest as the nutrient-limiting of glucose. There is no effect
of substrate concentration towards cell inhibition from 0.2 g/L to 2.0 g/L. Gas
chromatography was used to analyse the substrate, intermediates; (6R)-levodione and
(4S)-phorenol and main product (4R, 6R)-actinol. The concentration of (6R)-
levodione has higher concentration compared to (4S)-phorenol due to the competition
of coenzymes and higher rate of carbon-carbon double bond reduction compared to
the reaction rate of carbonyl reduction.