title: Biotransformation of D(+)-carnitine into L(-)-carnitine by resting cells of Escherichia coli O44 K74.
abstract: L(-)-carnitine was produced from D(+)-carnitine by resting cells of Escherichia coli O44 K74. Oxygen did not inhibit either the carnitine transport system or the enzymes involved in the biotransformation process. Aerobic conditions led to higher product yield than anaerobic conditions. The biotransformation yield depended both on biomass and initial substrate concentrations used; the selected values for these variables were 4.30 g l-1 cells and 100 mmol l-1 D(+)-carnitine. Under these conditions the L(-)-carnitine production rate was 0.55 g l-1 h-1, the process yield was 44%, and the productivity was 0.22 g l-1 h-1 after a 30 h incubation period. Crotonobetaine production, besides L(-)-carnitine, showed that the action of more than one enzyme occurred during the biotransformation process. On the other hand, the addition of fumarate at high substrate concentrations (250 and 500 mmol l-1) led to a higher metabolic activity, which meant an increment of L(-)-carnitine production.
authors.affiliation: Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Chemistry, University of Murcia, Spain.
authors.forename: M R
authors.initials: MR
authors.lastname: Castellar
authors.forename: M
authors.initials: M
authors.lastname: Cánovas
authors.forename: H P
authors.initials: HP
authors.lastname: Kleber
authors.forename: J L
authors.initials: JL
authors.lastname: Iborra
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001622:Betaine / Q000031:analogs & derivatives / Q000032:analysis; D018533:Biomass; D001711:Biotransformation; D002331:Carnitine / Q000737:chemistry / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D004926:Escherichia coli / Q000201:enzymology*; D005650:Fumarates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D013696:Temperature; D013997:Time Factors
chemical_list: D005650:Fumarates; D001622:Betaine; C025237:crotonic acid betaine; D002331:Carnitine