title: L(-)-carnitine production using a recombinant Escherichia coli strain.
abstract: The L(-)-carnitine production by biotransformation using the recombinant strain Escherichia coli pT7-5KE32 has been studied and optimized with crotonobetaine and D(+)-carnitine as substrates. A resting rather than a growing cells system for L(-)-carnitine production was chosen, crotonobetaine being the best substrate. High biocatalytic activity was obtained after growing the cells under anaerobic conditions at 37 degrees C and with crotonobetaine or L(-)-carnitine as inducer. The growth incubation temperature (37 degrees C) was high enough as to activate the heat-inducible lambdap(L) promoter inserted in the plasmid pGP1-2. The best biotransformation conditions were with resting cells, under aerobiosis, with 4 g l(-1) and 100 mM biomass and substrate concentrations respectively. Under these conditions the biotransformation time (1 h) was shorter and the L(-)-carnitine yield (70%) higher than previously reported. Consequently productivity value (11.3 g l(-1)h(-1)) was highly improved when comparing with other published works. The resting cells could be reused until eight times maintaining product yield levels well over 50% that meant to increase ten times the L(-)-carnitine obtained per gram of biomass.
authors.affiliation: Department of Biochemistry and Molecular Biology B and Immunology, Faculty of Chemistry, University of Murcia, P.O. Box 4021, E-30100, Murcia, Spain
authors.forename: M R.
authors.initials: MR
authors.lastname: Castellar
authors.forename: J M.
authors.initials: JM
authors.lastname: Obón
authors.forename: A
authors.initials: A
authors.lastname: Marán
authors.forename: M
authors.initials: M
authors.lastname: Cánovas
authors.forename: J L.
authors.initials: JL
authors.lastname: Iborra