Implementation of a Bio-Reaction System Requiring Cell Viability: Transformation of Carveol to Carvone with Rhodococcus erythropolis

Setembro 2001

Whole cells of Rhodococcus erythropolis DCL14 present carveol dehydrogenase (CDH) activity, which allows them to stereoselectively carry out the oxidation of the (+)-cis and (-)-trans-carveol to (+)- and (-)-carvone, respectively. When a diastereomeric mixture of (-)-carveol was supplied for biotransformation, the (-)-trans-carveol was converted to (-)-carvone. The major activity is NAD-dependent when the cells grow on limonene or cyclohexanol. The prolonged productivity of such a system depends on cell viability, since viable cells are naturally able to regenerate the co-factor. During the biotransformation cell viability was monitored off-line by fluorescence microscopy. The relatively low water solubility of carveol and carvone was overcome through the implementation of an organic:aqueous system. The most adequate phase ratio was 1:5, at which a stable emulsion is formed, for O.Ds. higher than 0.56. At an O.D. of 0.46 only half of the solvent was emulsified. Loss of viability increased with the O.D., probably due to oxygen shortage. At this scale the best aeration rate was found to be 0.01 vvm, both with regard to viability and stability of the emulsion. Carvone was found to be toxic, causing cell death at concentrations above 50 mM.

Autores da comunidade :

• 

  C

  Carla da Conceição Caramujo Rocha de Carvalho

  ist30853

  Afiliações e fontes

  IST > iBB

  Instituto de Bioengenharia e Biociências

  IST > DBE

  Departamento de Bioengenharia

• 

  M

  Maria Manuela Regalo da Fonseca

  ist12368

  Afiliações e fontes

  IST > iBB

  Instituto de Bioengenharia e Biociências

  IST > CEBQ

  Centro de Engenharia Biológica e Química

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Aveiro, Portugal

1129

1135

industrial-biotechnology - Biotecnologia Industrial

eng - Inglês