Peptaibol, Secondary‐Metabolite, and Hydrophobin Pattern of Commercial Biocontrol Agents Formulated with Species of the Trichoderma harzianum Complex

Abstract

The production of bioactive polypeptides (peptaibiotics) in vivo is a sophisticated adaptation strategy of both mycoparasitic and saprotrophic Trichoderma species for colonizing and defending their natural habitats. This feature is of major practical importance, as the detection of peptaibiotics in plant-protective Trichoderma species, which are successfully used against economically relevant bacterial and fungal plant pathogens, certainly contributes to a better understanding of these complex antagonistic interactions. We analyzed five commercial biocontrol agents (BCAs), namely Canna(®) , Trichosan(®) , Vitalin(®) , Promot(®) WP, and TrichoMax(®) , formulated with recently described species of the Trichoderma harzianum complex, viz. T. afroharzianum, T. simmonsii, and T. guizhouense. By using the well-established, HPLC/MS-based peptaibiomics approach, it could unequivocally be demonstrated that all of these formulations contained new and recurrent peptaibols, i.e., peptaibiotics carrying an acetylated N-terminus, the C-terminus of which is reduced to a 1,2-amino alcohol. Their chain lengths, including the amino alcohol, were 11, 14, and 18 residues, respectively. Peptaibols were also to be the dominating secondary metabolites in plate cultures of the four strains obtained from four of the Trichoderma- based BCAs, contributing 95% of the UHPLC-UV/VIS peak areas and 99% of the total ion count MS peak area from solid media. Furthermore, species-specific hydrophobins, as well as non-peptaibiotic secondary metabolites, were detected, the latter being known for their antifungal, siderophore, or plant-growth-promoting activities. Notably, none of the isolates produced low-molecular weight mycotoxins.

Diversity Profile and Dynamics of Peptaibols Produced by Green Mould Trichoderma Species in Interactions with Their Hosts Agaricus bisporus and Pleurotus ostreatus

“…simmonsii , where the sequences had an R3 position different in an Ala‐Aib exchange from hypomurocin B1 or B4, while a further 18‐residue peptaibol similar to hypomurocin B5 with the same difference in the R3 position was identified from T . harzianum . The 3D‐structural and folding properties of hypomurocins were recently characterised by Horváth et al …”

Metabolites from nematophagous fungi and nematicidal natural products from fungi as an alternative for biological control. Part I: metabolites from nematophagous ascomycetes

“…Among the approximately 30,000 known natural products from fungi, 15,000–16,000 are considered to be bioactive and almost 12,000 of them have been isolated from microscopic fungi (Bérdy 2012 ). For example, the beneficial role of antifungal peptidic and non-peptidic secondary metabolites in commercial biocontrol agents formulated with species of the Trichoderma harzianum complex (Chaverri et al 2015 ) has recently been demonstrated (Degenkolb et al 2015 ).…”

Visualizing fungal metabolites during mycoparasitic interaction by MALDI mass spectrometry imaging

“…Within peptaibiotics, peptaibols represent a subgroup of non‐ribosomal, membrane‐active linear chained polypeptides characterized by a C‐terminal alcohol residue, an acylated N‐terminus and a high level of unusual amino acids, like α‐aminoisobutyric acid (Aib), 2‐isovaline (Iva), and hydroxyproline (Hyp) . Up to now peptaibols were detected either from fungal spores by intact cell mass spectrometry (ICMS) or by well‐established HPLC‐MS/MS methods after isolation from cell cultures . Based on work using MSI in the field of microbiology , our objective was to develop a sample preparation method suitable for studying Trichoderma‐Rhizoctonia interactions directly from cultivation to visualize metabolite distributions induced by mycoparasite‐host interaction to build a solid basis for future work in the field of fungal communication.…”