Genetics of Lactic Acid Bacteria


There is a demand from the population for foods of high quality in sensory characteristics, nutritional value and the absence of toxic or potentially hazardous compounds for health. Lactic acid bacteria (LAB) are the main group of microorganisms used in the production of fermented foods. The survival of these microorganisms, which are continuously subjected to acid stress, is a fundamental line of research for the selection of LAB strains for food production.

The research is both fundamental and application-oriented for these microorganisms. We use Lactococcus lactis as a model starter culture for the dairy industry and as a vehicle for the production of compounds of pharmaceutical interest. On the other hand, Enterococcus faecalis and E. faecium are the object of study because they are on a thin line of food safety and because they constitute a health risk due to the presence of intrahospital multiresistant strains. We used approaches including Functional and Comparative Genomics of our model organisms and some other Gram-positive bacteria (pathogenic and non-pathogenic). Bioinformatics tools have been implemented to identify microorganisms and methodologies resulting from intense national and international collaborations.

Research Lines

K+ homeostasis in BAL and the role of c-di-AMP

c-di-AMP is a novel second messenger with fundamental biological functions in Gram-positive bacteria physiology and host immunity. This project aims to answer theoretical and applied aspects of c-di-AMP regulation in LAB and its application in the field of food and biopharmaceutical production. Of particular importance will be to describe the mechanisms mediated by c-di-AMP in potassium homeostasis within the diversity of LAB. We will use different complementary approaches including genetic techniques, biochemical characterization, metabolic analysis, microscopy, and gene expression analysis. We have both insect (Galleria Mellonella) and murine models of study. These multidisciplinary approaches will allow us to provide a complementary approach among the participating researchers. Recently, it has been demonstrated that c-di-AMP regulates a variety of cellular processes by binding to proteins and also to RNAm. The levels of c-di-AMP must be carefully adjusted in different environmental conditions to allow optimal growth, in many cases its presence is essential and high levels can be toxic to microorganisms. In addition, this compound is a potent adjuvant with immunomodulatory capacity in mice and is potentially applicable to vaccine development. The intracellular levels of c-di-AMP in bacteria are determined by the synthesis catalyzed by adenylate cyclases and by the degradation of this compound by different phosphodiesterases. This project aims to explore in depth the K+ transport system in Enterococcus faecalis, for this purpose we propose the construction of a system that allows biochemical characterization and interaction studies of c-di-AMP using the Lactococcus lactis model. Principal Investigator: Ch Magni –

Metaomics and livestock nutrition

The general objective of this line is to contribute to the improvement of silage quality for cattle by evaluating new biotechnological strategies. For this purpose, high-throughput sequencing techniques (metagenomics and metatranscriptomics) are used to study the complexity of the rumen and evaluate the impact of using recombinant lactic acid bacteria (LAB) as a technology to supplement or inoculate silages for cattle nutrition in the region.

Due to the importance of the rumen microbiota in ruminant nutrition and as a source of new enzymes of biotechnological interest, it is of our interest to characterize its composition at the level of microorganisms and enzymes encoded in this ecosystem. LAB are consumed daily by humans and used worldwide for the production and preservation of fermented foods. In this sense, we explore the use of recombinant LAB as safe bacteria to supplement or inoculate silage for livestock nutrition in the region. The impact on microbiological diversity will be analyzed through metatranscriptomics, which also will allow optimizing future LAB designs. Principal Investigator: V. Blancato -


Certain microorganisms present in food, contribute to the development of the flavor and aroma of food, but may also constitute a health risk for certain individuals. We propose to identify new factors that contribute to the infection or colonization process of Enterococcus, in strains isolated from clinical as well as from food environments. Using a bioinformatics approach, we selected probable virulence factors of microorganisms present in food in order to perform a comparative virulence analysis using the insect Galleria mellonella as a model; and also to study the virulence and regulatory mechanisms involved. Principal Investigator: V. Blancato -

Identification of metabolic pathways involved in the final quality of food

One of the mechanisms of resistance to acid stress is decarboxylation reactions. These systems are formed by a membrane transporter that allows the entry of the substrate and a specific decarboxylase. In Lactic acid bacteria (LAB), decarboxylations of organic acids (malate or citrate) and amino acids have been associated with acid stress resistance mechanisms. The citrate fermentation pathway is particularly important in the development of aroma and texture of certain types of cheeses and contributes to the aroma of wines. The main natural flavoring agent, diacetyl, is produced from this fermentation. The general objective of our studies is to delve into the mechanisms of regulation of gene expression in this important group of bacteria. We will delve into the beneficial and detrimental aspects resulting from the decarboxylating activity of certain metabolites in food production. Our working group has experience in studies on the mechanisms of gene expression regulation which remain unknown for this group of bacteria. The knowledge gained will allow us to understand when and why decarboxylations occur and to develop new strategies for the production of high-quality food. Principal Investigator: Ch Magni –

Selected Publications

  • Nasal immunization with a L. lactis-derived trans-sialidase antigen plus c-di-AMP protects against acute oral T. cruzi infection. Pacini, M.F., González, F.B., Dinatale, B., Magni C., Marcipar, I., Pérez, A.R. Vaccine, 2022, 40(15), pp. 2311–2323
  • Genomic analysis revealed conserved acid tolerance mechanisms from native micro-organisms in fermented feed. Terán, L.C., Mortera, P., Tubio, G., Esteban, L., Magni, C. Journal of Applied Microbiology, 2022, 132(2), pp. 1152–1165
  • The assessment of leading traits in the taxonomy of the Bacillus cereus group. Torres Manno, M.A., Repizo, G.D., Magni, C., Dunlap, C.A., Espariz, M. Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology, 2020, 113(12), pp. 2223–2242
  • Diversity of volatile organic compound production from leucine and citrate in Enterococcus faecium. D’Angelo, M., Martino, G.P., Blancato, V.S., Alarcón, S.H., Magni, C. Applied Microbiology and Biotechnology, 2020, 104(3), pp. 1175–1186
  • Enterococcus faecalis MalR acts as a repressor of the maltose operons and additionally mediates their catabolite repression via direct interaction with seryl-phosphorylated-HPr. Grand, M., Blancato, V.S., Espariz, M., Magni, C., Sauvageot, N. Molecular Microbiology, 2020, 113(2), pp. 464–477
  • The KupA and KupB proteins of Lactococcus lactis IL1403 are novel c-di-AMP receptor proteins responsible for potassium uptake. Quintana, I.M., Gibhardt, J., Turdiev, A., Magni, C., Stülke, J. Journal of Bacteriology, 2019, 209(10), e00028-19
  • GeM-Pro: a tool for genome functional mining and microbial profiling. Torres Manno, M.A., Pizarro, M.D., Prunello, M., Daurelio, L.D., Espariz, M. Applied Microbiology and Biotechnology, 2019, 103(7), pp. 3123–3134
  • Implications of the expression of Enterococcus faecalis citrate fermentation genes during infection. Martino, G.P., Perez, C.E., Magni, C., Blancato, V.S. PLoS ONE, 2018, 13(10), e0205787
  • Genetic and phenotypic features defining industrial relevant Lactococcus lactis, L. cremoris and L. lactis biovar. diacetylactis strains. Torres Manno, M., Zuljan, F., Alarcón, S., Espariz, M., Magni, C. Journal of Biotechnology, 2018, 282, pp. 25–31
  • Genetic engineering of Lactococcus lactis co-producing antigen and the mucosal adjuvant 3' 5'- cyclic di Adenosine Monophosphate (c-di-AMP) as a design strategy to develop a mucosal vaccine prototype. Quintana, I., Espariz, M., Villar, S.R., Blancato, V., Magni, C. Frontiers in Microbiology, 2018, 9(SEP), 2100 user=ceIEjZ8AAAAJ&hl=es