ABSTRACT

Plant growth-promoting bacteria (PGPB) can promote plant health through stimulation of the plant’s immune system. A key advantage of the use of bacteriophages as biocontrol agents is their specificity for target bacteria. The synthesis of antibiotics is most commonly associated with the ability of PGPB to suppress plant pathogen development. PGPB can improve the quality and nutritional value of seeds and fruits, contributing to an increase in food and feed yield and quality. The positive effects caused by PGPB on plant growth may result from direct and/or indirect mechanisms. Direct mechanisms of plant growth promotion include growth stimulation by phytohormones and improvement of nutrient acquisition through processes such as atmospheric nitrogen fixation, iron sequestration, and phosphate solubilization. Microorganisms able to solubilize phosphate have assisted in the phytoremediation of heavy metal-impacted soil. Many PGPB are able to synthesize and modulate phytohormones under in vitro conditions, and the physiological traits are thought to be essential assets for new plant-beneficial strains.