Soil-borne fungal pathogens such as Sclerotium spp., Rhizoctonia spp., and Macrophomina spp. pose significant threats to global agriculture, with soybean crops among the most severely affected due to damping-off disease. These pathogens cause substantial yield losses, making their management a critical concern. In this study, we investigated the potential of Bacillus siamensis BCL, a novel Neotropical strain, as an eco-friendly solution for managing Sclerotium, Rhizoctonia, and Macrophomina species. The strain exhibited strong antifungal activity, significantly inhibiting fungal growth in vitro, with the greatest suppression observed against Macrophomina spp., reaching up to 81%. In vivo assays further confirmed the biocontrol potential of B. siamensis. When applied at 10⁶ colony-forming units (CFU)/mL, the strain reduced disease symptoms and improved plant growth parameters—including root length, shoot biomass, and leaf number—compared to untreated, infected controls. The protective effect varied by pathogen, with the most significant recovery in root length observed against Macrophomina spp. (85%) and Sclerotium spp. (78%). In preventive treatments, fermentation extracts of the B. siamensis strain suppressed disease progression, although they did not promote seedling growth. A genomic analysis of B. siamensis BCL revealed genes encoding antimicrobial secondary metabolites, including terpenes, fengycins, and surfactins. These findings highlight B. siamensis BCL as a promising candidate for sustainable crop protection and a valuable resource for developing novel antimicrobial strategies in agriculture.

Brown spot, caused by the seedborne fungus Bipolaris oryzae, remains a major constraint in rice production. Here, we used in vitro and in vivo assays to evaluate the biocontrol potential of three Bacillus strains (Ba. cereus OQ725688.1, Ba. velezensis OP938696.1, and Ba. subtilis OP937353.1) against Bi. oryzae in two rice cultivars (“Rubelita” and “Predileta”). Ba. cereus showed the highest in vitro mycelial inhibition (≈95%), whereas Ba. velezensis was the most effective under greenhouse conditions, reducing disease severity by up to 60% and increasing seedling vigor by 51% compared with infected controls. “Predileta” showed the strongest response to bacterial treatment, maintaining severity scores below 2 even under high inoculum pressure. Functional assays confirmed that all strains displayed amylolytic, catalase, and phosphate-solubilizing activities, with Ba. velezensis uniquely expressing strong cellulase and protease activities. Genome analysis of Ba. velezensis OP938696.1 revealed multiple biosynthetic gene clusters for antifungal polyketides and lipopeptides. These integrated biochemical and genomic traits demonstrate the novelty and potential of this Neotropical strain as a multifunctional agent capable of suppressing Bi. oryzae while enhancing rice seedling performance. Incorporating such a native strain into seed and soil management offers a sustainable strategy for rice protection in Neotropical systems.

Phytic acid is an antinutritional factor in cereal feeds, and the use of phytases increases the bioavailability of nutrients bound to this molecule. However, the application of these enzymes depends on their thermal stability and activity at acidic pH. Therefore, in this study we created a database composed of 59 phytase sequences and analyzed the interactions that stabilize their structures in order to understand whether they contribute to the biochemical properties observed. The sequences were aligned and grouped at 30 % similarity, generating 5 clusters, which highlights the high variability among them. A comparative structural analysis of the cluster 3 phytases revealed conserved catalytic domains, as well as eight cysteine residues along the primary sequence, forming disulfide bonds for stabilizing the three-dimensional structure. However, the number of Van der Waals, ionic, and hydrogen interactions, and disulfide bonds was not determinant for the biochemical characteristics presented by these enzymes. The phytase KM873028, from cluster 3, was selected for characterization studies, but its expression in Pichia pastoris generated a protein with properties distinct from those derived from the same sequence expressed in a prokaryotic system. It is likely that the differences observed are associated with the location of the interactions in the structures, non-conserved amino acid residues found around the catalytic site, and post-translational modifications inherent to the expression systems. These possibilities highlight the relevance of strategic choices related to enzyme expression aiming at its production and industrial feasibility.

Endophytic bacteria play a pivotal role in plant health by modulating nutrient availability, growth regulation, and resistance to phytopathogens. However, the functional diversity and ecological significance of the endophytic bacteria in rice (Oryza sativa L.) plants remain incompletely understood. Here, we functionally characterized the diversity of endophytic bacteria isolated from healthy rice plants and evaluated their potential roles in plant growth promotion and fungal pathogen suppression under in vitro conditions. We recovered 23 bacterial isolates from roots, stems, and leaves and identified them, by means of 16S rRNA gene sequencing, as members of the genera Pseudomonas, Enterobacter, and Bacillus. Phylogenetic analysis confirmed the dominance of these genera across plant tissues. Functional characterization revealed pronounced isolate-dependent variability in the production of indole-3-acetic acid (IAA) and ammonia, and in the ability to solubilize essential macro- and micronutrients. Most isolates efficiently solubilized phosphorus (P), while potassium (K) solubilization was particularly prevalent among Bacillus isolates. In contrast, silicon (Si) and zinc (Zn) solubilization were restricted to a smaller subset of isolates, indicating functional specialization within the endophytic community. Antagonistic assays demonstrated that of the 23 isolates tested, 6 isolates inhibited the growth of Bipolaris oryzae, whereas strong suppression of Pyricularia oryzae was observed only for one Pseudomonas and one Enterobacter isolate. Limited inhibitory activity was detected against Rhizoctonia solani, which highlights pathogen-specific interactions. Altogether, our findings indicate that rice harbors functionally diverse endophytic bacteria with complementary in vitro traits related to nutrient mobilization, phytohormone production, and pathogen suppression. These results identify candidate isolates for further validation. In planta, greenhouse, and field studies are now required to establish whether these traits translate into improved plant growth, nutrient uptake, or disease control.