Preface, 1. Probiotic Social Life, Biochemical Cross-talk and Ecological Relationships Among Bacteria, 2. Fighting Off Human Infections: A New Role for Bacteriocin Molecules, 3. Lactic Acid Bacteria to Modulate Virulence Expression in Pathogenic Bacteria: An Alternative to Killing?, 4. Probiotic-Mediated Modulation of Host Gene Expression, 5. Bifidobacteria and their Interaction with the Gastrointestinal Environment, 6. New Probiotics: Dairy Propionibacteria and the Modulation of Gut Microbiota and Physiology, 7. Neuro-active Compounds Produced by Probiotics: Towards a Microbiota-(Gut-) Brain Axis Control?, 8. Nutraceutical and Antioxidant Potential of Probiotics: The Case of Selenium Fixing Bacteria and Selenium Enriched Yeasts, 9. The Double Face of Bacteria and the Ambiguous Role of Some Probiotics, 10. Probiotics Meets Proteomics: How Proteomics Can Contribute to Risk Assessment and Biomolecular Understanding, 11. Prebiotic Enhancement of Probiotic Potential: Oligosaccharides Triggering Modification of Protein Profiles in Lactic Acid Bacteria, Index, Color Plate Section