Metabolism of L(-)-carnitine by Enterobacteriaceae under aerobic conditions

Different Enterobacteriaceae, such as Escherichia coli, Proteus vulgaris an d Proteus mirabilis, are able to convert L(-)carnitine, via crotonobetaine, into gamma-butyrobetaine in the presence of carbon and nitrogen sources un der aerobic conditions. Intermediates of L(-)-carnitine metabolism (crotono betaine, gamma-butyrobetaine) could be detected by thin-layer chromatograph y. In parallel, L(-)-carnitine dehydratase, carnitine racemasing system and crotonobetaine reductase activities were determined enzymatically. Monoclo nal antibodies against purified CaiB and CaiA from E. coli O44K74 were used to screen cell-free extracts of different Enterobacteriaceae (E. coli ATCC 25922, P. vulgaris, P. mirabilis, Citrobacter freundii, Enterobacter cloac ae and Klebsiella pneumoniae) grown under aerobic conditions in the presenc e of L(-)-carnitine. (C) 1999 Federation of European Microbiological Societ ies. Published by Elsevier Science B.V. All rights reserved.