Abstract
Trichoderma spp. are known as biocontrol agents of fungal plant pathogens and have been recognized as a potential source of bioactive metabolites. The production of antimicrobial substances from strains T. atroviride (TS) and T. asperellum (IMI 393899) was investigated. The bioactivity of 10- and 30-day culture filtrate extracted with ethyl acetate was assessed against a set of pathogenic fungi and oomycetes. The 30-day extracts of both strains had significant cytotoxic effects against the tested pathogens, with values of minimum fungicidal concentration (MFC) ranging between 0.19 and 6.25 mg/mL. Dual culture assay (direct contact and nondirect contact) and the percentage inhibition of radial growth (PIRG) was calculated. The highest PIRG values were 76% and 81% (direct contact) with IMI 393899 and TS, respectively. Nondirect contact does not show inhibition on any of pathogens tested, indicating that the inhibition is not due to the secretion of volatile substances. Culture filtrates were analyzed by GC-MS and HPLC-Q-TOF-MS for the identification of volatile organic compounds (VOCs) and nonvolatile organic compounds (nVOCs), respectively. Seven classes of VOCs and 12 molecules of nVOCs were identified. These results indicate that these strains of Trichoderma had antimicrobial activities and they are potential natural sources of compounds with biological activity.
Highlights
Synthetic chemicals, such as fertilizers, herbicides and pesticides, used in horticultural production systems and during postharvest processes are environmental pollutants and potentially harmful to humans and animals [1]
The results of the antifungal activity of nonvolatile or diffusible compounds obtained with the two Trichoderma strains tested, T. asperellum IMI 393899 and T. atroviride TS, showed that the extracted antifungal compounds inhibited the growth of all pathogens in the agar diffusion assay, as shown in
The two Trichoderma strains tested in this study, T. asperellum IMI 393899 and T. atroviride TS, The two strains testedwhen in this study, and T. the atroviride TS, inhibited the Trichoderma growth of tested pathogens they came T
Summary
Synthetic chemicals, such as fertilizers, herbicides and pesticides, used in horticultural production systems and during postharvest processes are environmental pollutants and potentially harmful to humans and animals [1]. The excessive use of broad-spectrum synthetic fungicides can affect the microbiome of the rhizosphere, including symbiotic fungi and beneficial bacteria. These microorganisms interact with the plants, modifying and promoting the availability of nutrients in the soil, such as nitrogen fixation [2]. The excessive use of synthetic chemicals in farming systems has led governmental and international institutions to limit their use and shift interest towards sustainable food and agriculture (FAO, 2020). A valid alternative to synthetic fungicides is the use of biocontrol agents and/or their metabolites. Several biocontrol agents are recognized including bacterial, such as Agrobacterium, Bacillus, and Pseudomonas, and
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