1. Introduction Part I. Microbial Ecology in Food Security 2. Microbial Interactions iIn Agroecosystems 3. Plant-Pathogen Interactions: Mechanisms Involved in Plant Diseases 4. Biological Control Agents for Mitigating Plant Diseases 5. Plant Growth Promoting Bacteria as a Sustainable Agricultural Strategy Part II. Development of Next-Generation Bacterial Inoculants 6. Bioprospection of Beneficial Bacteria for Bioproducts Innovation in Agriculture 7. Molecular and Biochemical Responses of Plants to Bacterial Inoculants 8. Omics Approaches for Detecting Action Modes of Microbial Inoculants 9. Polyphasic Taxonomic of Strains Contained in Bacterial Inoculants 10. Bacterial Inoculants Production Systems 11. Bioformulation of Bacterial Inoculants 12. Performance Evaluation of Bacterial Inoculants in the Field Part III. Present and Future Scenario 13. The Role of Microbial Culture Collections in the Bioinoculants Development 14. Legal Framework for the Development of Microbial Inoculants 15. Perspectives and Challenges for Innovating Microbial Inoculants