Effect of the steroidal plant growth promoter SPGP4 on the microbial diversity of soils cultivated with maize and beans

Soil microbial diversity is of great importance for plant development, as well as for the control of pathogens through the production of metabolites. In this study, the effect of the compound 22-Oxocholestanes SPGP4, an analogue of brassinosteroids, on microbial diversity was evaluated when applied to soils where maize and beans are grown.  The soils were analyzed using metagenomic study to determine the populations of bacteria and fungi before and after the application of the compound. The results show that the main bacterial Phyla are Actinobacteria, Acidobacteriota, and Proteobacteria; while the main genera are Bacillus, Streptomyces, Nocardioides, Vicinamibacteraceae, Solirubrobacter and Sphingomonas were the most abundant. With regard to fungi, the main Phyla were Ascomycota and Basidiomycota; the main genera being Aspergillus, Fusarium, Chrysocorona, Penicillium, Humicola, Chaetomium and Curvularia. The alpha diversity showed that there was no significant difference (p> 0.05) in the soil microbial communities, which indicates that the application of 22-Oxocholestanes SPGP4 at a concentration of 0.5 mg/L does not affect the microbial diversity of the soils.