Genetic organization and expression of citrate permease in lactic acid bacteria.
Citrate is present in many natural substrates, such as milk, vegetables and fruits, and its metabolism by lactic acid bacteria (LAB) plays an important role in food fermentation. The industrial importance of LAB stems mainly from their ability to convert carbohydrates into lactic acid and, in some species, like Lactococcus lactis and Leuconostoc mesenteroides, to produce C4 flavor compounds (diacetyl, acetoin) through citrate metabolism. Three types of genetic organization and gene locations, involving citrate metabolism, have been found in LAB. Citrate uptake is mediated by a citrate permease, which leads to a membrane potential upon electrogenic exchange of divalent citrate and monovalent lactate. The internal citrate is cleaved into acetate and oxaloacetate by a citrate lyase, and oxaloacetate is decarboxylated into pyruvate by an oxaloacetate decarboxylase, yielding a pH gradient through the consumption of scalar protons.
Drider
Djamel
D
Laboratoire de Microbiologie Alimentaire et Industrielle (QM2A), ENITIAA, rue de la Géraudière BP 82225, 44322 Nantes cedex 3, France.
Bekal
Sadjia
S
Prévost
Hervé
H
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D003931:Diacetyl / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D019344:Lactic Acid / Q000378:metabolism*; D017045:Lactococcus / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism; D016366:Open Reading Frames; D027361:Organic Anion Transporters / Q000235:genetics* / Q000378:metabolism; D007652:Oxo-Acid-Lyases / Q000235:genetics* / Q000378:metabolism; D027981:Symporters
D001426:Bacterial Proteins; D002352:Carrier Proteins; C096373:CitP protein, Lactobacillales; D004269:DNA, Bacterial; D009097:Multienzyme Complexes; D027361:Organic Anion Transporters; D027981:Symporters; D019344:Lactic Acid; C065431:citP protein, Lactococcus lactis; D007652:Oxo-Acid-Lyases; C019909:citrate (pro-3S)-lyase; D003931:Diacetyl