The use of plant growth-promoting bacteria (PGPB) represents an eco-friendly alternative to the application of chemical fertilizers and pesticides in agriculture. Many PGPB strains, belonging to genera such as Acinetobacter spp., Bacillus spp., Enterobacter spp., Pseudomonas spp., offer beneficial effects on plant growth, improve nutrient availability, and help to control the attacks by plant pathogens. Unfortunately, several PGPB strains exhibit antimicrobial resistance due to the presence of antibiotic resistance genes (ARGs), which may be transferred to indigenous soil microorganisms. This transfer may lead to ARGs entering in the food chain and affecting the human microbiome, with potential health consequences. The main mechanism of ARGs action includes: a reduced antibiotic uptake, the target site modification, and the activation of efflux pumps. Although PGPB are promoted as sustainable tools, their use could inadvertently promote the spread of multidrug-resistant bacteria. Therefore, the monitoring of ARGs in biofertilizers, using conventional and innovative methods, is essential to ensure product safety, regulatory compliance, and efficacy. The future development and large-scale applications of bacteria-based biofertilizers must include rigorous screening of bacterial strains for antibiotic resistance profile, biosafety level classification, and environmental monitoring, in order to minimize the risk of ARGs dissemination.
Suggested by Dr. Alessandro Pietrosanti