The increasing demand for sustainable plant protection products has intensified interest in microbial biocontrol agents (BCAs). This study aimed to evaluate the antifungal activity of selected Streptomyces, Bacillus, and Trichoderma asperellum strains against phytopathogenic fungi and to assess their potential as BCAs under in vitro conditions. The antifungal activity of ten Streptomyces strains was first evaluated against Botrytis cinerea, Colletotrichum salicis, Fusarium oxysporum, and F. graminearum using a dual-culture assay. All isolates exhibited antifungal activity, with Streptomyces venezuelae MSCL 350 showing the strongest inhibition. In addition, the antifungal activity of T. asperellum MSCL 309 and three Bacillus strains was assessed against twelve Fusarium spp. isolates obtained from oats. T. asperellum demonstrated broad-spectrum inhibition, with growth inhibition ranging from 44.6% to 78.4%, primarily due to soluble metabolites, while volatile compounds showed no significant effect. Among the other tested Bacillus strains, only Bacillus subtilis MSCL 1441 exhibited antifungal activity, inhibiting all tested isolates. These results demonstrate strong strain-dependent antifungal activity and highlight T. asperellum MSCL 309, S. venezuelae MSCL 350, and B. subtilis MSCL 1441 as promising candidates for the development of environmentally friendly biocontrol agents.
Seņkovs et al. (Thu,) studied this question.