title: Enhanced biotransformations and product recovery in a membrane bioreactor through application of a direct electric current.
abstract: 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.
authors.affiliation: Department of Earth Sciences, University of Oxford, 62 Banbury Road, Oxford OX2 6PN, United Kingdom.
authors.forename: Roberta
authors.initials: R
authors.lastname: Mustacchi
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Knowles
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Ian
authors.initials: I
authors.lastname: Dalrymple
authors.forename: Garry
authors.initials: G
authors.lastname: Sunderland
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Skibar
authors.forename: Simon A
authors.initials: SA
authors.lastname: Jackman
mesh_terms: D000619:Aminohydrolases / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology*; D001711:Biotransformation; D004560:Electricity; D009570:Nitriles / Q000378:metabolism; D012240:Rhodococcus / Q000201:enzymology*
chemical_list: D009570:Nitriles; D000619:Aminohydrolases; C021867:nitrilase