Plant-Growth-Promoting Microorganisms in Sustainable Agriculture: From Biological Mechanisms to Circular Bioeconomy

Plant-growth-promoting microorganisms (PGPMs) have emerged as important biological tools for improving plant nutrition, crop productivity, soil health, and resilience to environmental stresses, contributing to more resource-efficient agricultural systems. This review provides a comprehensive overview of recent advances in PGPM research, with particular emphasis on next-generation microbial technologies, including synthetic microbial communities, advanced bioformulations, omics-based approaches, precision agriculture, and their contribution to the circular bioeconomy. This review combines a narrative synthesis with a bibliometric analysis based on a dataset of 801 English-language articles and review papers retrieved from the Web of Science Core Collection on 22 May 2026. Bibliometric mapping identified a rapidly expanding and increasingly interdisciplinary research landscape centered on microbial biostimulants, biofertilizers, circular economy, soil health, microbiome engineering, and climate-smart agriculture. This narrative synthesis highlights that advances in multi-omic technologies, microbiome research, and formulation strategies are improving our understanding of plant–microbe interactions and supporting the development of more targeted microbial products. At the same time, widespread agricultural implementation remains constrained by inconsistent field performance, limited ecological validation, formulation challenges, fragmented regulatory frameworks, and insufficient long-term biosafety assessments. Future research should prioritize long-term field validation across diverse agroecosystems, standardized efficacy and safety evaluation, integration of artificial intelligence with multi-omics datasets, development of ecologically reliable microbial consortia, and regulatory harmonization to facilitate responsible commercialization.