Plant growth promoting rhizobacteria (PGPR) play a crucial role in sustainable agriculture by enhancing plant growth and reducing reliance on synthetic fertilizers and pesticides. PGPR improve plant growth through various mechanisms, including nutrient solubilization, hormone production, and disease resistance. They also help in abiotic stress tolerance, such as salinity and drought, by improving water use efficiency and nutrient uptake. PGPR can be classified into symbiotic and free-living bacteria, with symbiotic bacteria living inside plant cells and free-living bacteria residing in the rhizosphere. The direct and indirect mechanisms of PGPR include biofertilization, root growth stimulation, and biological control of plant pathogens. PGPR are effective in promoting plant growth by producing phytohormones such as auxins, gibberellins, cytokinins, and ethylene, which regulate plant development. They also produce siderophores to enhance iron availability to plants and volatile organic compounds that induce systemic resistance against pathogens. Additionally, PGPR can produce enzymes like chitinase and glucanase that inhibit fungal growth. However, some PGPR species may have negative effects, such as producing cyanide or rhizobitoxine, which can be harmful to plants. The use of PGPR as biofertilizers is gaining importance due to their ability to enhance soil fertility and crop yield. Nano-encapsulation technology is being explored to improve the efficacy of PGPR by protecting them from environmental stressors and enhancing their survival and activity in the soil. This technology allows for controlled release of PGPR, ensuring their effectiveness in promoting plant growth and improving agricultural sustainability. The integration of nanotechnology in agriculture is essential to meet the growing demand for food while minimizing environmental impact. Overall, PGPR offer a sustainable solution for improving agricultural productivity and reducing the use of chemical fertilizers and pesticides.Plant growth promoting rhizobacteria (PGPR) play a crucial role in sustainable agriculture by enhancing plant growth and reducing reliance on synthetic fertilizers and pesticides. PGPR improve plant growth through various mechanisms, including nutrient solubilization, hormone production, and disease resistance. They also help in abiotic stress tolerance, such as salinity and drought, by improving water use efficiency and nutrient uptake. PGPR can be classified into symbiotic and free-living bacteria, with symbiotic bacteria living inside plant cells and free-living bacteria residing in the rhizosphere. The direct and indirect mechanisms of PGPR include biofertilization, root growth stimulation, and biological control of plant pathogens. PGPR are effective in promoting plant growth by producing phytohormones such as auxins, gibberellins, cytokinins, and ethylene, which regulate plant development. They also produce siderophores to enhance iron availability to plants and volatile organic compounds that induce systemic resistance against pathogens. Additionally, PGPR can produce enzymes like chitinase and glucanase that inhibit fungal growth. However, some PGPR species may have negative effects, such as producing cyanide or rhizobitoxine, which can be harmful to plants. The use of PGPR as biofertilizers is gaining importance due to their ability to enhance soil fertility and crop yield. Nano-encapsulation technology is being explored to improve the efficacy of PGPR by protecting them from environmental stressors and enhancing their survival and activity in the soil. This technology allows for controlled release of PGPR, ensuring their effectiveness in promoting plant growth and improving agricultural sustainability. The integration of nanotechnology in agriculture is essential to meet the growing demand for food while minimizing environmental impact. Overall, PGPR offer a sustainable solution for improving agricultural productivity and reducing the use of chemical fertilizers and pesticides.