Mechanisms of the biostimulant action of Bacillus spp

The use of microorganisms that stimulate the growth and development of plants is an alternative to the use of synthetic fertilizers in conventional agricultural production. Previous research has shown that bacteria from the genus Bacillus exert a biostimulating effect on various cultivated plant species. These bacteria have numerous direct and indirect mechanisms of action due to their great metabolic diversity. Certain Bacillus spp. increase the availability of nutrients through biological nitrogen fixation and phosphate solubilization in the soil, which directly affects plant growth. Also, Bacillus spp. produce phytohormones that affect the growth and development of plants, the most important of which are auxins, gibberellins and cytokinins. This paper discusses the most important mechanisms of action of Bacillus spp. and provides an overview of previous research on the effectiveness of these bacteria on different plant species. Knowledge of the mechanisms of action is essential for the successful application of preparations based on Bacillus spp. and achieving stable yields.