BackgroundThe biogenic synthesis of metallic nanoparticles is a green alternative that reduces the toxicity of this nanomaterials and may enable a synergy between the metallic core and the biomolecules employed in the process enhancing biological activity. The aim of this study was to synthesize biogenic titanium nanoparticles using the filtrate of the fungusTrichoderma harzianumas a stabilizing agent, to obtain a potential biological activity against phytopathogens and mainly stimulate the growth ofT. harzianum, enhancing its efficacy for biological control.ResultsThe synthesis was successful and reproductive structures remained in the suspension, showing faster and larger mycelial growth compared to commercialT. harzianumand filtrate. The nanoparticles with residualT. harzianumgrowth showed inhibitory potential againstSclerotinia sclerotiorummycelial growth and the formation of new resistant structures. A great chitinolytic activity of the nanoparticles was observed in comparison withT. harzianum. In regard to toxicity evaluation, an absence of cytotoxicity and a protective effect of the nanoparticles was observed through MTT and Trypan blue assay. No genotoxicity was observed on V79-4 and 3T3 cell lines while HaCat showed higher sensitivity. Microorganisms of agricultural importance were not affected by the exposure to the nanoparticles, however a decrease in the number of nitrogen cycling bacteria was observed. In regard to phytotoxicity, the nanoparticles did not cause morphological and biochemical changes on soybean plants.ConclusionThe production of biogenic nanoparticles was an essential factor in stimulating or maintaining structures that are important for biological control, showing that this may be an essential strategy to stimulate the growth of biocontrol organisms to promote more sustainable agriculture.Graphical Abstract