There are numerous studies that have shown the benefits of plant growth promoting rhizobacteria (PGPR) in agriculture; within these are the production of plant growth hormones such as indolacetic acid, gibberellins and cytokinins, the transformation of nutrients to a form assimilated by plants such as nitrogen and phosphorus, production of siderophores that act as iron chelators, and also, some of these bacteria can act as antagonists of some pathogenic microorganisms. However, despite all the benefits these bacteria offer by acting mainly as biofertilizers and bioremediation, little is known about the possible negative effects that these microorganisms can have organisms, especially humans. There are a few case studies of patients who have gone to the hospital for a condition caused by different species of plant growth-promoting bacteria. Therefore, in this review some of the positive studies and negative reports of some rhizobacteria species in the last decade are described.
Key words: agriculture, bacteria, biofertilizers, humans, negative effect.