Biotechnological Applications of Plant Growth-Promoting Rhizobacteria for Sustainable Agriculture

Abstract

Plant growth-promoting rhizobacteria (PGPR) are beneficial soil microorganisms that have emerged as promising biological tools for improving crop productivity and promoting sustainable agriculture. This review examines the major mechanisms and biotechnological applications of PGPR, with particular emphasis on their use as biofertilizers, biocontrol agents, and promoters of plant tolerance to environmental stresses. PGPR can enhance plant growth through biological nitrogen fixation, phosphate solubilization, siderophore production, phytohormone synthesis, ACC deaminase activity, and improvement of root development. They can also suppress plant pathogens through competition, production of antimicrobial compounds, secretion of lytic enzymes, nutrient sequestration, and induction of systemic resistance in plants. These properties enable PGPR to improve nutrient-use efficiency, plant growth, disease resistance, and tolerance to drought, salinity, and other abiotic stresses. The review further highlights the potential of PGPR-based biofertilizers as sustainable alternatives or supplements to synthetic fertilizers and chemical pesticides. However, their effectiveness under field conditions can vary due to soil properties, environmental factors, bacterial strain characteristics, root colonization ability, and interactions with indigenous microbial communities. Therefore, the development of effective formulations, locally adapted strains, compatible microbial consortia, and reliable field-scale application strategies is essential for successful commercialization. Overall, PGPR represent an important component of sustainable agricultural biotechnology and have considerable potential to enhance crop productivity while reducing environmental impacts associated with intensive chemical inputs.