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Enhanced biotransformations and product recovery in a membrane bioreactor through application of a direct electric current.

Research output: Contribution to journalJournal article


  • Roberta Mustacchi
  • Christopher J. Knowles
  • Hong Li
  • Ian Dalrymple
  • Garry Sunderland
  • Wolfgang Skibar
  • Simon A. Jackman
Journal publication date5/01/2005
JournalBiotechnology and Bioengineering
Journal number1
Number of pages6
Original languageEnglish


The simultaneous enhancement of biotransformation coupled to product recovery, purification and concentration is presented. The nitrilase of Rhodococcus rhodochrous LL100-21 catalyses the single-step hydrolytic biotransformation of benzonitrile to benzoic acid and ammonia. When a direct electric current is applied across a bioreactor containing the bacterium and benzonitrile, the charged product (benzoic acid) can be removed in situ across an anion exchange membrane and recovered in a separate compartment. Over the course of a 24-hour biotransformation, benzonitrile was converted to benzoic acid which was completely removed from the bioreactor chamber and concentrated 3-fold in a separate chamber. The rate of production of benzoic acid increased by 42% when the current was applied (0.044 mmol/min/g dry cell weight in the presence of current as compared to 0.03 mmol/min/g dry cell weight in its absence). The enhanced reaction rate was achieved irrespective of product separation and therefore appears to be a direct effect upon the bacterial cells. This process has potential for enhanced productivity from biotransformations through a simultaneous increase in metabolic activity and in situ product recovery.

Bibliographic note

Funded by: the United Kingdom Department of Trade and Industry and the Biotechnology and Biological Sciences Research Council