Microbial biotechnology and host-pathogen interaction


1. Structure and function of bacterial proteins that modulate virulence expression


Trapping of Escherichia coli cells in a dielectrophoresis chip

Protein–protein and protein–DNA interactions play key roles in the ability of virulent bacteria to adapt to the host environment and cause disease. A group of proteins is currently the focus of our research: nucleoid-associated proteins (NAPs) that contribute to DNA architecture and modulate gene expression. We are interested in unravelling the role played by two of these proteins – Hha and H-NS – in the regulation of virulence and of plasmid transfer. Escherichia coli pathotypes such as enteroaggregative E. coli are the subject of our research. Owing to their key modulatory functions, these proteins are interesting targets to combat bacterial infections.

2. Bacterial plasmids and their role in transmission of multidrug resistance markers

A main concern with bacterial infections is the selection of isolates that are resistant to several antimicrobial drugs. The transmission of the ability of bacterial cells of simultaneously resist several antimicrobial drugs is accomplished, in many instances, by plasmids. These genetic elements can be transmitted from one cell to another, and modify the phenotype of the recipient cell. We have recently shown that multidrug resistance plasmids in Salmonella require specific plasmid proteins to be stably maintained in this microorganism. These proteins could be considered as targets to combat multidrug resistance.

3. Application of nanotools of bacterial biotechnology

Hha perturbing H-NS structure

Hha perturbing H-NS structure

3.1. Dielectrophoresis. We have previously shown that dielectrophoresis can be a valuable tool for bacterial cell sorting and characterization. We are currently using different chip designs (2D and 3D carbon electrodes) to: a) study the effect of electric fields on bacterial cell physiology; b) combine DEP with other molecular protocols for detection and identification of different types of cells. Recent results have shown that DEP chips can be used to increase PCR detection of yeast cells.

3.2. Atomic force microscopy (AFM). Conventional AFM approaches have been shown to be powerful techniques for characterizing both biomaterials and biomolecules. In a joint project with the Nanoscale Bioelectrical Characterization group (page 76), we intend to use electrical- AFM to characterize the bacterial cell envelope. We also plan to use this approach to analyze the structural and physiological properties of bacterial living cells.



IBEC internal collaboration succeeds in measuring bacterial cell response to electrical fields

Two groups working together at IBEC demonstrate the potential of electrical studies of single bacterial cells in a paper published in ACS Nano. Gabriel Gomila’s Nanoscale Bioelectrical Characterization group and that of Antonio Juárez, Microbial Biotechnology and Host-pathogen Interaction, combined their expertise on microscopic electrical measurements and bacteria respectively to come up with a way to study the response to external electrical fields of just a single bacterial cell.

Antibiotic resistance: a ‘devastating’ public health issue

A researcher’s paper published in the journal Environmental Microbiology is just one step in the right direction to tackle a major public health issue that he and other experts say could soon be devastating.

“El combate contra la pseudomona en manos del Dr. Torrents”

Senior researcher Eduard Torrents appears several times in the July edition of the newspaper of the Associació Catalana de Fibrosi Quística, Per a Vèncer la Fibrosi Quística.

Continuing the fight against cystic fibrosis

IBEC Senior Researcher Eduard Torrents participated in a conference to mark the National Day for Cystic Fibrosis last Wednesday 25 April. This event, which took place at the Spanish Society of Pneumology and Thoracic Surgery (SEPAR), also included the official presentation of funds from the Associació Catalana de Fibrosis Quística (Catalan Association of Cystic Fibrosis) to research groups specializing in the disease.

Joining forces to beat Salmonella

An IBEC group has embarked on a technology transfer venture together with two biopharmaceutical companies. Antonio Juárez’s Microbial Technology and Host-Pathogen Interaction lab has formed a consortium with CZV Veterinaria, a leader in the manufacture of veterinary products based in Porriño, Galicia, and Valls Companys’ pharmaceutical arm MEVET in Lleida. Their two-year project aims to obtain strains of Salmonella with weakened virulence, which can then be used to develop a vaccine to reduce the incidence of the infection in poultry farms. Salmonella, a leading cause of food poisoning, is zoonotic, able to spread to man through contaminated animal food products.

Opening new doors to combat bacterial infections

We may be several steps closer to understanding one of the major pathologies that affects sufferers of cystic fibrosis, thanks to Senior researcher Eduard Torrents of IBEC’s Microbial biotechnology and host-pathogen interaction group

IBEC researcher receives Pablo Motos award

Eduard Torrents, senior researcher in IBEC’s Microbial Biotechnology and Host-pathogen Interaction group, has been announced as a recipient of the 2010 Pablo Motos award from the Federación Española de Fibrosis Quística (Spanish Association of Cystic Fibrosis) this week.

IBEC to host Sociedad Española de Microbiología group congress

This week IBEC will be hosting the 8th meeting of the Molecular Microbiology group of the Sociedad Española de Microbiología (SEM). The congress will offer the chance for participants to learn about noteworthy advances in the field and to discuss the particular trends and challenges in this area.

Discovery of the key to the success of some of the most virulent bacteria

Researchers at IBEC, IRB Barcelona and the UB identify the strategy used by enterobacteria to acquire resistance and pathogenicity.

The Cystic Fibrosis Association of Catalonia supports research study at IBEC

The Cystic Fibrosis Association of Catalonia (Asociación Catalana de Fibrosis Quística) provides active support to the research conducted by Doctor Eduard Torrents, a member of IBEC´s Microbial Biotechnology and Host-Pathogen Interaction Group, into the enzyme that promotes the growth of the bacteria linked to this disease.


National projects
Regulación de la virulencia bacteriana por proteínas que reconocen conformaciones locales del ADN REGVIRBAC Antonio Juárez
INTERMODS Interconexiones de Módulos plasmídicos y los Genomas de Bacterias Patógenas MINECO-CSIC Antonio Juárez (managed by UB)
Privately funded projects
MEJORAVE1 Mejora sanitaria y de productos cármicos de ave Industrial project with Mevet, S.A – CZ Veterinaria, S.A Antonio Juárez


Hüttener, Mario, Paytubi, Sonia, Juárez, Antonio, (2015). Success in incorporating horizontally transferred genes: the H-NS protein Trends in Microbiology 23, 2, 67-69

Solórzano, Carla, Srikumar, Shabarinath, Canals, Rocío, Juárez, Antonio, Paytubi, Sonia, Madrid, Cristina, (2015). Hha has a defined regulatory role that is not dependent upon H-NS or StpA Frontiers in Microbiology 6, Article 773 [Open Access]

Barreiros dos Santos, M., Azevedo, S., Agusil, J. P., Prieto-Simón, B., Sporer, C., Torrents, E., Juárez, A., Teixeira, V., Samitier, J., (2015). Label-free ITO-based immunosensor for the detection of very low concentrations of pathogenic bacteria Bioelectrochemistry 101, 146-152

Van Der Hofstadt, M., Hüttener, M., Juárez, A., Gomila, G., (2015). Nanoscale imaging of the growth and division of bacterial cells on planar substrates with the atomic force microscope Ultramicroscopy 154, 29-36

Del Moral Zamora, B., Álvarez Azpeitia, J.M., Oliva Brañas, A.M., Colomer-Farrarons, J., Castellarnau, M., Miribel-Català, P., Homs-Corbera, A., Juárez, A., Samitier, J., (2015). Continuous flow dielectrophoretic concentrator enhancement based on dielectric poles Electrophoresis 36, 13, 1405–1413

Jaramillo, Maria del Carmen, Huttener, Mario, Alvarez, Juan Manuel, Homs-Corbera, Antoni, Samitier, Josep, Torrents, Eduard, Juárez, Antonio, (2015). Dielectrophoresis chips improve PCR detection of the food-spoiling yeast Zygosaccharomyces rouxii in apple juice Electrophoresis 36, 13, 1471-1478

del Moral Zamora, Beatriz, Manuel Álvarez Azpeitia, Juan, Brañas, Ana Ma Oliva, Colomer-Farrarons, Jordi, Castellarnau, Marc, Miribel-Català, Pere Ll, Homs-Corbera, Antoni, Juárez, Antonio, Samitier, Josep, (2015). Dielectrophoretic concentrator enhancement based on dielectric poles for continuously flowing samples Electrophoresis 36, 13, 1405-1413

Oliva, A. M., Homs-Corbera, A., Torrents, E., Juarez, A., Samitier, J., (2014). Synergystic effect of temperature and electric field intensity in Escherichia coli inactivation Micro and Nanosystems 6, 2, 79-86

del Moral Zamora, B., Azpeitia, J. M. Á, Farrarons, J. C., Català, P. L. M., Corbera, A. H., Juárez, A., Samitier, J., (2014). Towards point-of-use dielectrophoretic methods: A new portable multiphase generator for bacteria concentration Micro and Nanosystems 6, 2, 71-78

Esteban-Ferrer, Daniel, Edwards, Martin Andrew, Fumagalli, Laura, Juarez, Antonio, Gomila, Gabriel, (2014). Electric polarization properties of single bacteria measured with electrostatic force microscopy ACS Nano 8, 10, 9843–9849

Paytubi, S., Aznar, S., Madrid, C., Balsalobre, C., Dillon, S. C., Dorman, C. J., Juárez, A., (2014). A novel role for antibiotic resistance plasmids in facilitating Salmonella adaptation to non-host environments Environmental Microbiology 16, 4, 950-962

Gibert, M., Juárez, A., Zechner, E. L., Madrid, C., Balsalobre, C., (2014). TrhR, TrhY and HtdA, a novel regulatory circuit that modulates conjugation of the IncHI plasmids Molecular Microbiology 94, 5, 1146-1161

Dietrich, M., Pedró, L., García, J., Pons, M., Hüttener, M., Paytubi, S., Madrid, C., Juárez, A., (2014). Evidence for moonlighting functions of the Journal of Bacteriology 196, 5, 1102-1112

Hüttener, M., Dietrich, M., Paytubi, S., Juárez, A., (2014). HilA-like regulators in Escherichia coli pathotypes: the YgeH protein from the enteroaggregative strain 042 BMC Microbiology 14, 268, 1-10

Oliva, A. M., Homs, A., Torrents, E., Juarez, A., Samitier, J., (2014). Effect of electric field and temperature in E.Coli viability IFMBE Proceedings Springer 41, 1833-1836

del Moral Zamora, B., Azpeitia, J. M. Á, Farrarons, J. C., Català, P. L. M., Corbera, A. H., Juárez, A., Samitier, J., (2014). Towards point-of-use dielectrophoretic methods: A new portable multiphase generator for bacteria concentration IFMBE Proceedings Springer International Publishing 41, 856-859

Jaramillo, M. C., Martínez-Duarte, R., Hüttener, M., Renaud, P., Torrents, E., Juárez, A., (2013). Increasing PCR sensitivity by removal of polymerase inhibitors in environmental samples by using dielectrophoresis Biosensors and Bioelectronics 43, 1, 297-303

Otero, J., Baños, R., González, L., Torrents, E., Juárez, A., Puig-Vidal, M., (2013). Quartz tuning fork studies on the surface properties of Pseudomonas aeruginosa during early stages of biofilm formation Colloids and Surfaces B: Biointerfaces 102, 117-123

Aznar, Sonia, Paytubi, Sonia, Juárez, Antonio, (2013). The Hha protein facilitates incorporation of horizontally acquired DNA in enteric bacteria Microbiology 159, 3, 545-554

Rodríguez-Hernández, Ana G., Muñoz-Tabares, José, Godoy-Gallardo, Maria, Juárez, Antonio, Gil, Francisco-Javier, (2013). S. sanguinis adhesion on rough titanium surfaces: Effect of culture media Materials Science and Engineering: C 33, 2, 714-720

Cendra, M. M., Juárez, A., Madrid, C., Torrents, E., (2013). H-NS is a novel transcriptional modulator of the ribonucleotide reductase genes in escherichia coli Journal of Bacteriology 195, 18, 4255-4263

Gilbert, M., Juárez, A., Madrid, C., Balsalobre, C., (2013). New insights in the role of HtdA in the regulation of R27 conjugation Plasmid Elsevier 70 (1), 61-68

Paytubia, S., Dietrich, M., Queiroz, M.H., Juárez, A., (2013). Role of plasmid- and chromosomally encoded Hha proteins in modulation of gene expression in E. coli O157:H7 Plasmid Elsevier 70 (1), 52-60

Cendra, M. d M., Juárez, A., Torrents, E., (2012). Biofilm modifies expression of ribonucleotide reductase genes in Escherichia coli PLoS ONE 7, 9, e46350

Cordeiro, T. N., Schmidt, H., Madrid, C., Juarez, A., Bernado, P., Griesinger, C., Garcia, J., Pons, M., (2011). Indirect DNA readout by an H-NS related protein: Structure of the DNA complex of the C-terminal domain of Ler Plos Pathogens 7, 11, 12

Crona, Mikael, Torrents, Eduard, Rohr, Asmund K., Hofer, Anders, Furrer, Ernst, Tomter, Ane B., Andersson, K. Kristoffer, Sahlin, Margareta, Sjoberg, Britt-Marie, (2011). NrdH-redoxin protein mediates high enzyme activity in manganese-reconstituted ribonucleotide reductase from bacillus anthracis Journal of Biological Chemistry 286, 38, 33053-33060

Sjoberg, B. M., Torrents, E., (2011). Shift in ribonucleotide reductase gene expression in pseudomonas aeruginosa during infection Infection and Immunity 79, 7, 2663-2669

Pedro, L., Banos, R. C., Aznar, S., Madrid, C., Balsalobre, C., Juarez, A., (2011). Antibiotics shaping bacterial genome: Deletion of an IS91 flanked virulence determinant upon exposure to subinhibitory antibiotic concentrations PLoS ONE 6, 11, 11

de Alba, C. F., Solorzano, C., Paytubi, S., Madrid, C., Juarez, A., Garcia, J., Pons, M., (2011). Essential residues in the H-NS binding site of Hha, a co-regulator of horizontally acquired genes in Enterobacteria FEBS Letters 585, 12, 1765-1770

Queiroz, Mário H., Madrid, Cristina, Paytubi, Sònia, Balsalobre, Carlos, Juárez, Antonio, (2011). Integration Host Factor alleviates H-NS silencing of the Salmonella enterica serovar Typhimurium master regulator of SPI1, hilA Microbiology-Sgm 157, 9, 2504-2514

Banos, R. C., Aznar, S., Madrid, C., Juarez, A., (2011). Differential functional properties of chromosomal- and plasmid-encoded H-NS proteins Research in Microbiology 162, 4, 382-385

Rodríguez-Hernández, Ana, Juárez, A., Engel, E., Gil, F., (2011). Streptococcus sanguinis adhesion on titanium rough surfaces: effect of shot-blasting particles Journal of Materials Science: Materials in Medicine Springer Netherlands 22, 8, 1-10

Banos, R. C., Martinez, J., Polo, C., Madrid, C., Prenafeta, A., Juarez, A., (2011). The yfeR gene of Salmonella enterica serovar Typhimurium encodes an osmoregulated LysR-type transcriptional regulator Fems Microbiology Letters 315, 1, 63-71

Adrados, B., Julian, E., Codony, F., Torrents, E., Luquin, M., Morato, J., (2011). Prevalence and concentration of non-tuberculous Mycobacteria in cooling towers by means of quantitative PCR: A prospective study Current Microbiology 62, 1, 313-319

Paytubi, S., Garcia, J., Juarez, A., (2011). Bacterial Hha-like proteins facilitate incorporation of horizontally transferred DNA Central European Journal of Biology 6, 6, 879-886

Lundin, Daniel, Gribaldo, Simonetta, Torrents, Eduard, Sjoberg, Britt-Marie, Poole, Anthony, (2010). Ribonucleotide reduction - horizontal transfer of a required function spans all three domains BMC Evolutionary Biology 10, 1, 383

Torrents, E., Sjoberg, B. M., (2010). Antibacterial activity of radical scavengers against class Ib ribonucleotide reductase from Bacillus anthracis Biological Chemistry 391, 2-3, 229-234

Jaramillo, M. D., Torrents, E., Martinez-Duarte, R., Madou, M. J., Juarez, A., (2010). On-line separation of bacterial cells by carbon-electrode dielectrophoresis Electrophoresis 31, 17, 2921-2928

Johansson, R., Torrents, E., Lundin, D., Sprenger, J., Sahlin, M., Sjöberg, B. M., Logan, D. T., (2010). High-resolution crystal structures of the flavoprotein NrdI in oxidized and reduced states – an unusual flavodoxin FEBS Journal 277, 20, 4265-4277

Banos, R. C., Vivero, A., Aznar, S., Garcia, J., Pons, M., Madrid, C., Juarez, A., (2009). Differential regulation of horizontally acquired and core genome genes by the bacterial modulator H-NS PLoS Genetics 5, 6, 8

Lundin, Daniel, Torrents, Eduard, Poole, Anthony, Sjoberg, Britt-Marie, (2009). RNRdb, a curated database of the universal enzyme family ribonucleotide reductase, reveals a high level of misannotation in sequences deposited to Genbank BMC Genomics 10, 1, 589

Garcia, J., Madrid, C., Cendra, M., Juarez, A., Pons, M., (2009). N9L and L9N mutations toggle Hha binding and hemolysin regulation by Escherichia coli and Vibrio cholerae H-NS FEBS Letters 583, 17, 2911-2916

Torrents, E., Sahlin, M., Sjöberg, B., (2009). The ribonucleotide reductase family: genetics and genomics Nova Science Publishers , 99

Roca, Ignasi, Torrents, Eduard, Sahlin, Margareta, Gibert, Isidre, Sjoberg, Britt-Marie, (2008). NrdI essentiality for class Ib ribonucleotide reduction in streptococcus pyogenes Journal of Bacteriology 190, 14, 4849-4858

Cordeiro, Tiago N., García, Jesús, Pons, José-Ignacio, Aznar, Sonia, Juárez, Antonio, Pons, Miquel, (2008). A single residue mutation in Hha preserving structure and binding to H-NS results in loss of H-NS mediated gene repression properties FEBS Letters 582, 20, 3139-3144

Banos, R. C., Pons, J. I., Madrid, C., Juarez, A., (2008). A global modulatory role for the Yersinia enterocolitica H-NS protein Microbiology 154, 5, 1281-1289

Castellarnau, M., Zine, N., Bausells, J., Madrid, C., Juarez, A., Samitier, J., Errachid, A., (2008). ISFET-based biosensor to monitor sugar metabolism in bacteria Materials Science & Engineering C Elsevier Science 28, 5-6, 680-685

Castellarnau, Marc, Errachid, Abdelhamid, Madrid, Cristina, Juárez, Antonio, Samitier, Josep, (2006). Dielectrophoresis as a tool to characterize and differentiate isogenic mutants of Escherichia coli Biophysical Journal 91, 10, 3937-3945


  • Dielectrophoresis equipment
  • Thermocycler (PCR)
  • Protein and DNA electrophoresis
  • Process of biomolecule production
  • Protein expression and purification systems
  • Technology of microbial culture facilities


  • Prof. Charles Dorman
    Trinity College, Dublin
  • Dr. Eduard Torrents
  • Dr. Rodrigo Martínez-Duarte
    École Polytechnique Fédérale de Lausanne
  • Prof. Josep Casadesús
    Universidad de Sevilla
  • Prof. F. García del Portillo
    Centro Nacional de Biotecnología, Madrid
  • Dr. Gabriel Gomila
  • Prof. Mike Hughes
    University of Surrey (UK)
  • Prof. Josep Samitier
  • Prof. Miquel Pons
    Organic Chemistry Dept., University of Barcelona, Spain

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