Optimising The Production Of Chiral Alcohol Via Aspergilus Niger Catalysed Biotransformation Of 1-(4-Bromo-Phenyl)-Ethanone
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Date
2011-11
Authors
Abas, Fatimatul Zaharah
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Publisher
Universiti Sains Malaysia
Abstract
Chiral alcohols are useful starting materials for the synthesis of various biologically active compounds. In this study, the biocatalytic reduction of ketone via asymmetric reduction process using Aspergillus niger as a whole-cell biocatalyst was carried out in order to produce (R)-1-(4-bromo-phenyl)-ethanol. From the result obtained in this sudy, it shows that the exponential phase was the best period for biotransformation to take place compared to the stationary phase, since the production rate (0.063 mM/h) at exponential phase was higher than the production rate (0.028 mM/h) at stationary phase. In addition, the optimization study for biotransformation via shake-flask system shows that the optimum condition was found to be at 48th hr incubation time under pH 6.68 and at 31.85oC with the lowest amount of substrate concentration which is 6.78 mM. The highest % enantiomeric excess and product conversion which almost 100 % were achieved at this optimum condition. The increasing amount of substrate concentration used in this biotransformation process leads to substrate inhibition. In addition by using the bioreactor system, it can maximize the % of enantiomeric excess, production conversion, and rate of product formation. The parameters varied on bioreactor system were agitation speed in the ranges of 50 rpm to 150 rpm and the incubation time of biotransformation from 0 to 56th h. From result obtained, the maximum agitation speed was found to be at 150 rpm with optimum incubation time at 33.34th
hr of biotransformation with 99.94 % e.e and 88.22 % product conversion. In addition, almost 0.097 mM/h of the production rate was achieved at this optimum condition.
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Keywords
Optimising the production of chiral alcohol , via Aspergilus niger catalysed biotransformation