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.

The present review summarises data on the prevalence and concentration of fusaproliferin, beauvericin and enniatins in small grains, maize and processed grain-based foods. These fungal secondary metabolites possess interesting biological activities and are presently often referred to as 'emerging mycotoxins'. They have been considered as less important since they are likely not of acute toxicity. However, their high prevalence in foodstuffs, occasionally in higher mg/kg concentrations, warrants an assessment of their true importance for food (and feed) safety. Thorough surveys that determine the contamination of raw and processed foods with fusaproliferin, beauvericin and enniatins are still scarce and are generally limited to Northern Europe and the Mediterranean. The reported data suggest a connection between the observed concentrations and climate. The data further suggest that humans might be exposed continuously to low levels of enniatins as these compounds were of particularly high prevalence in the surveys. The highest concentrations of enniatins were reported from Spain and Northern Africa (maximum concentration of enniatin A₁ 814 mg/kg in rice from the Spanish market), while concentrations were significantly lower in Northern Europe (maximum concentration of enniatin B 18.3 mg/kg in wheat from Finland). Beauvericin appears to be of low significance in grains from cooler climates while it has been reported to occur at concentrations of tens of mg/ kg in Southern Europe and Morocco (maximum concentration 59 mg/kg in maize from Morocco). Fusaproliferin has been least investigated. Several reports from the Mediterranean show its occasional occurrence up to 19.6 mg/ kg in rice from Morocco, while its natural occurrence in cooler climates seems to be more rare.