1. Probiotic social life, biochemical cross-talk and ecological relationships among bacteria / Enrica Pessione -- 2. Fighting off human infections : a new role for bacteriocin molecules / Konstantinos Papadimitriou, Voula Alexandraki and Effie Tsakalidou -- 3. Lactic acid bacteria to modulate virulence expression in pathogenic bacteria : an alternative to killing? / Sergine Even, Damien Bouchard and Yves Le Loir -- 4. Probiotic-mediated modulation of host gene expression / Sarah O'Flaherty -- 5. Bifidobacteria and their interaction with the gastrointestinal environment / Borja Sanchez, Irene Gonzalez-Rodriguez, Clara G. de los Reyes-Gavilan, Patricia Ruas-Madiedo and Abelardo Margolles -- 6. New probiotics : dairy propionibacteria and the modulation of gut microbiota and physiology / Stephanie-Marie Deutsch and Gwenael Jan -- 7. Neuro-active compounds produced by probiotics : towards a microbiota-(gut-) brain axis control? / Roberto Mazzoli -- 8. Nutraceutical and antioxidant potential of probiotics : the case of selenium fixing bacteria and selenium enriched yeasts / Erika Mangiapane -- 9. The double face of bacteria and the ambiguous role of some probiotics / Alessandro Pessione -- 10. Probiotics meets proteomics : how proteomics can contribute to risk assessment and biomolecular understanding / Stephan Fuchs and Katharina Riedel -- 11. Prebiotic enhancement of probiotic potential : oligosaccharides triggering modification of protein profiles in lactic acid bacteria / Avishek Majumder, Morten Ejby, Gabriella C. van Zanten, Anne Knudsen, Sampo J. Lahtinen, Birte Svensson and Susanne Jacobsen.