title: Glutamate-induced metabolic changes in Lactococcus lactis NCDO 2118 during GABA production: combined transcriptomic and proteomic analysis.
abstract: GABA is a molecule of increasing nutraceutical interest due to its modulatory activity on the central nervous system and smooth muscle relaxation. Potentially probiotic bacteria can produce it by glutamate decarboxylation, but nothing is known about the physiological modifications occurring at the microbial level during GABA production. In the present investigation, a GABA-producing Lactococcus lactis strain grown in a medium supplemented with or without glutamate was studied using a combined transcriptome/proteome analysis. A tenfold increase in GABA production in the glutamate medium was observed only during the stationary phase and at low pH. About 30 genes and/or proteins were shown to be differentially expressed in glutamate-stimulated conditions as compared to control conditions, and the modulation exerted by glutamate on entire metabolic pathways was highlighted by the complementary nature of transcriptomics and proteomics. Most glutamate-induced responses consisted in under-expression of metabolic pathways, with the exception of glycolysis where either over- or under-expression of specific genes was observed. The energy-producing arginine deiminase pathway, the ATPase, and also some stress proteins were down-regulated, suggesting that glutamate is not only an alternative means to get energy, but also a protective agent against stress for the strain studied.
authors.affiliation: Dipartimento di Biologia Animale e dell'Uomo, Università di Torino, Via Accademia Albertina 13, 10123, Torino, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Mazzoli
authors.forename: Enrica
authors.initials: E
authors.lastname: Pessione
authors.forename: Magali
authors.initials: M
authors.lastname: Dufour
authors.forename: Valérie
authors.initials: V
authors.lastname: Laroute
authors.forename: Maria Gabriella
authors.initials: MG
authors.lastname: Giuffrida
authors.forename: Carlo
authors.initials: C
authors.lastname: Giunta
authors.forename: Muriel
authors.initials: M
authors.lastname: Cocaign-Bousquet
authors.forename: Pascal
authors.initials: P
authors.lastname: Loubière
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D018698:Glutamic Acid / Q000378:metabolism*; D013294:Lactococcus lactis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D040901:Proteomics; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid