Harnessing microbially fortified compost extracts to enhance rhizosphere dynamics and sustainably suppress Fusarium wilt in tomato

The risks associated with pesticide use have driven the search for sustainable alternatives. In this context, aqueous compost extracts, rich in bioactive compounds and beneficial microorganisms, have emerged as a promising strategy for plant protection by supporting both plant nutrition al and phytopathogen control. This study aimed to characterize an aqueous extract derived from vegetable waste compost and to evaluate the effect microbial fortification through inoculation with two microbial strains exhibiting glucanolytic and chitinolytic activities, followed by a one-week incubation period. Microbial abundance, functional metabolic diversity, and bacterial community structure were assessed, along with their effects on the rhizosphere and plant health in response to Fusarium oxysporum f.sp. lycopersici . Microbial enrichment resulted in an increased abundance of key microbial groups, as well as enhanced metabolic activity and diversity. In addition, fortification induced a clear shift in microbial community structure, reducing taxonomic dominance and promoting the establishment of inoculated bacterial families commonly associated with plant growth promotion and biocontrol. Application of the extracts via irrigation led to a rapid but transient increase in microbial abundance in the tomato rhizosphere. By the end of the experiment, treated plants exhibited improved vegetative development, with the fortified extract showing a consistent phytostimulant effect. Furthermore, pre-treatment with compost extracts effectively reduced disease severity caused by F. oxysporum. Overall, these results demonstrate that aqueous compost extracts contribute to disease mitigation, while microbial fortification further modulates microbial community structure and enhances agronomic performance, supporting their potential as a sustainable strategy for managing biotic stress in crops. • Bioaugmentation boosts microbial load and metabolic activity in compost extracts • Microbial enrichment increases microbiome diversity and richness in compost extract • Compost extracts promote rapid beneficial microbial colonization in the rhizosphere • Fortified compost extracts show significant phytostimulant effects on tomato plants • Preventive application reduces damage from Fusarium oxysporum f.sp. lycopersici