Effect of PGPB-enriched organic fertilizer ORGAON®PK on the rhizospheric microbiota and biomass of Lupinus albus (L.): a sustainable alternative to chemical fertilizer

The intensive use of agrochemicals is essential to maintain crop yields, but it has led to overexploitation of land and environmental deterioration. To promote more sustainable agriculture, this study evaluates the novel effects of biofertilizers enriched with plant growth promoting bacteria, such as Bacillus pretiosus and Pseudomonas agronomica, on Lupinus albus var. Orden Dorado, to improve the rhizospheric soil health and plant biomass as well as reducing dependence on chemical fertilizers. The organic matrix ORGAON^®PK and its sterilized version, both derived from horticultural waste, were tested compared with a traditional chemical fertilizer and a water control. After three months of treatment, metagenomic analyses (16 S rRNA gene amplicons) indicated that the strains remained in the rhizosphere, increasing metabolic diversity without altering the microbial structure (Shannon index). In addition, a significant reduction in the minimum inhibitory concentration against clinical antibiotics (p < 0.05) was observed, highlighting the potential of biofertilizers to decrease microbial resistance in the soil. Principal component analysis showed clear differences between treated and control groups, and ANCOM-BC revealed changes in non-culturable bacteria. Biometric analyses revealed increases of 70-88% in shoot weight, ~ 80% in total biomass, and up to 36% in shoot elongation compared with the control. Biofertilizers improved nutritional quality and plant biomass, suggesting their potential as a sustainable and efficient alternative to the use of chemical fertilizers.