Genetics of Lactic Acid Bacteria

Summary

There is a demand in the population for high quality food, with high nutritional value, good sensorial characteristics, and lacking toxic components or potentially dangerous for health. Lactic acid bacteria constitute the main group of microorganisms in the production of fermented food. The survival of these microorganisms, which are continuously subjected to acid stress, constitutes an important line of research for the selection of LAB strains destined to food production.

Research Lines

Genetics of Lactic Acid Bacteria

There is a demand in the population for high quality food, with high nutritional value, good sensorial characteristics, and lacking toxic components or potentially dangerous for health. Lactic acid bacteria constitute the main group of microorganisms in the production of fermented food. The survival of these microorganisms, which are continuously subjected to acid stress, constitutes an important line of research for the selection of LAB strains destined to food production. One of the mechanisms of resistance to acid stress are decarboxylation reactions. These systems are formed by a membrane transporter, which allows the entry of the substrate, and a specific decarboxylase. Decarboxylation of organic acids (malate or citrate) and amino acids have been associated with mechanisms of resistance to acid stress in LB. The pathway of citrate fermentation is particularly important in the development of the aroma and texture of certain types of cheese, and also contributes to the aroma of wine. One of the products of this fermentation, diacetyl, is the main natural aroma compound. The general objective of our studies is to gain insight into the gene expression regulatory mechanisms of this important group of bacteria. In aspect related to beneficial and prejudicial features that result from the decarboxylation of certain metabolites in food production. Our research group has experience in studies of gene expression regulatory mechanisms, which still remain unknown for this group of bacteria. The acquired knowledge will allow us to understand in which conditions the decarboxylations are produced and to develop new production strategies for high quality food.

Selected Publications

  • Suárez C, Espariz M, Blancato VS, Magni C. Expression of the Agmatine Deiminase Pathway in Enterococcus faecalis Is Activated by the AguR Regulator and Repressed by CcpA and PTS(Man) Systems (2013) PLoS One. 14;8(10):e76170. doi: 10.1371/journal.pone.0076170.
  • Mortera P, Pudlik A, Magni C, Alarcón S, Lolkema JS. Ca2+-citrate uptake and metabolism in Lactobacillus casei ATCC 334. (2013) Appl Environ Microbiol. 79(15):4603-12. doi: 10.1128/AEM.00925-13
  • Repizo GD, Blancato VS, Mortera P, Lolkema JS, Magni C. Biochemical and genetic characterization of the Enterococcus faecalis oxaloacetate decarboxylase complex (2013) Appl Environ Microbiol. 79(9):2882-90. doi: 10.1128/AEM.03980-12.
  • Mokhtari A, Blancato VS, Repizo GD, Henry C, Pikis A, Bourand A, de Fátima Álvarez M, Immel S, Mechakra-Maza A, Hartke A, Thompson J, Magni C, Deutscher J. Enterococcus faecalis utilizes maltose by connecting two incompatible metabolic routes via a novel maltose 6'-phosphate phosphatase (MapP) (2013). Mol Microbiol. 88(2):234-53. doi: 10.1111/mmi.12183.
  • Suárez C, Repizo G, Espariz M, Blancato V, Magni C, Alarcón S. Detection and identification of tyrDC+ enterococcal strains from pasteurized commercial chesses. (2012) Food Science and Biotechnology 21 (2) , 603-606
  • Mortera P, Espariz M, Suárez C, Repizo G, Deutscher J, Alarcón S, Blancato V, Magni C..Fine-Tuned Transcriptional Regulation of Malate Operons in Enterococcus faecalis. Appl Environ Microbiol. (2012) ;78:1936-1945.
  • Draft genome sequence of enterococcus mundtii CRL1656. Magni, C., et al (2012) Journal of Bacteriology 194:550.
  • Genome sequence of the bacteriocin-producing Lactobacillus curvatus strain CRL705. Hebert, E.M., et al (2012) Journal of Bacteriology 194:538-539.
  • Disruption of the alsSD operon of Enterococcus faecalis impairs growth on pyruvate at low pH. Repizo, G.D., Mortera, P., Magni, C. 2011 Microbiology 157 :. 2708-2719.
  • CcpA represses the expression of the divergent cit operons of Enterococcus faecalis through multiple cre sites. Suárez, C.A., Blancato, V.S., Poncet, S., Deutscher, J., Magni, C. (2011) BMC microbiology 11: 227.
  • Identification of malic and soluble oxaloacetate decarboxylase enzymes in Enterococcus faecalis. Espariz, M., Repizo, G., Blancato, V., Mortera, P., Alarcõn, S., Magni, C. (2011) FEBS Journal 278 : 2140-2151.
  • Oral immunization with live Lactococcus lactis expressing rotavirus VP8* subunit induces specific immune response in mice. Marelli, B., Perez, A.R., Banchio, C., de Mendoza, D., Magni, C. (2011) Journal of Virological Methods 175:28-37.Biogenic amines in fermented foods. Spano, G., et al 2010 European Journal of Clinical Nutrition 64: S95-S100.
  • A simple expression system for Lactococcus lactis and Enterococcus faecalis. Marelli, B., Magni, C. (2010) World Journal of Microbiology and Biotechnology 26 999-1007.
  • Production of human growth hormone by Lactococcus lactis. Margolles, A., Moreno, J.A., Ruiz, L., Marelli, B., Magni, C., de los Reyes-Gavilán, C.G., Ruas-Madiedo, P. (2010) Journal of Bioscience and Bioengineering 109. 322-324.
  • A chimeric vector for efficient chromosomal modification in enterococcus faecalis and other lactic acid bacteria. Blancato, V.S., Magni, C. (2010) Letters in Applied Microbiology 50 : 542-546.

Collaborators

  • Dra. Lopez, Paloma, Consejo Superior de Investigaciones Científicas. Estructura y Función de Proteinas. Centro de Investigaciones Biológicas. E-mail: plg@cib.csic.es; Velázquez 144. 28006 Madrid, España.
  • Dr. Juke S. Lolkema, Dpto. de Microbiología. Groningen Biomolecular Sciences and Biotechnology Institute. University of Groningen. Email: j.s.lolkema@rug.nl; Kerklaan 30. 9751 NN Haren Gn, Holanda.
  • Dr. Josef Deustcher. Laboratoire de Génétique des Microorganismes, Thiverval-Grignon, Francia.

Grants

  • Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).
  • Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT).
  • Fermentation of Food Products: “Controlling Biogenic Amines in Traditional Food Fermentations in Regional Europe” de la Comision de Comunidades Europeas “Quality of Life and Management of Living Resources”. Director Juke Lolkema, 2009-2011.
  • Proyecto de colaboración Internacional Eco-SUD Mincyt (Argentina) - (Francia) Responsable Dr. Ch Magni, Dr. J. Deutscher. “Mecanismos moleculares de la represión catábolica en bacterias grampositivas”. 2010-2012.

Director

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Magni, Christian
Core Faculty
Email: magni@ibr-conicet.gov.ar
Phone: +54 341 4350596/4350661
Office Extension: 120
Laboratory Extension: 118

Researchers

  • Víctor Blancato
  • Martín Espariz

Doctoral fellows

  • Ingrid Quintana
  • Gabriela Martino

Undergraduate Students

  • Cristian Perez

Imágenes

Metabolismo de citrato en Bacterias Lácticas.