Harnessing Bacillus and Paenibacillus: metabolic and genetic characterization for the development of biopreparations for plant pathogen control

The development of effective and stable microbial biopreparations is essential for sustainable plant protection and for assessing the status of environmental microorganisms and phytopathogens.This study investigated the metabolic and ecological capacities of Bacillus and Paenibacillus species with potential roles in pathogen biocontrol.Therefore, organic-compliant liquid biopreparations were formulated using bacterial strains in combination with plant extracts, humic acids, and/or vinasse -components influence on microbial metabolism and antagonistic activity.Individual formulation ingredients were evaluated for their antagonistic properties, compatibility with beneficial bacteria, and their effects on microbial viability and functional activity during storage.Antagonistic assays demonstrated that nettle leaf and horsetail herb extracts effectively inhibited the growth of phytopathogens while preserving the proliferation of beneficial bacteria, indicating selective disruption of pathogen cellular integrity and metabolism.Scanning electron microscopy (SEM) and NanoLive holotomography imaging confirmed the structural stabilization of the final biopreparation.The liquid formulations maintained bacterial viability and functional stability for at least three months at both room temperature and 4°C, meeting industrial standards for microbial product shelf-life.These findings highlight that biopreparations enriched with ecological, biologically safe ingredients have strong potential for application in crop protection against pathogen infections, supporting the development of sustainable biocontrol strategies.