Production of TMC- 151, TMC- 154 and TMC- 171, a new class of antibiotics, is specific to ‘Gliocladium roseum’ group

Accumulation of antitumor polyketides by fermentation of Rubus delavayi Franch. with Clonostachys rogersoniana

The aim of this work is to explore the effects of herbal medicine on secondary metabolites of microorganisms during fermentation. Clonostachys rogersoniana was found to metabolize only small amounts of polyketide glycosides rogerson B and C on fresh potatoes, but after replacing the medium to the medicinal plant Rubus delavayi Franch., the type and content of the metabolized polyketones showed significant changes. The sugars and glycosides in R. delavayi are probably responsible for the changes in secondary metabolites. Six polyketide glycosides including a new metabolite, rogerson F, and two potential antitumor compounds, TMC-151C and TMC-151D, were isolated from the extract of R. delavayi fermented by C. rogersoniana. In addition, 13C labeling experiments were used to trace the biosynthesis process of these compounds. TMC-151C and TMC-151D showed significant cytotoxic activity against PANC-1, K562 and HCT116 cancer cells but had no obvious cytotoxic activity against BEAS-2B human normal lung epithelial cells. The yields of TMC-151C and TMC-151D reached 14.37 ± 1.52 g/kg and 1.98 ± 0.43 g/kg, respectively, after fermentation at 28 °C for 30 days. This is the first study to confirm that herbal medicine can induce microbes to metabolize active compounds. And the technology of fermenting medicinal materials can bring more economic value to medicinal plants.

Asperphenalenones Isolated from the Biocontrol Agent Clonostachys rosea and Their Antimicrobial Activities

Clonostachys rosea is a fungus widely distributed on Earth and has a high capacity to adapt to complex environments in soil, plants, or sea. It is an endophyte that can be used as a potential biocontrol agent to protect plants from pathogenic fungi, nematodes, and insects. However, the spectrum of secondary metabolites produced by C. rosea has only scarcely been studied. In the present study, eight new phenalenones, asperphenalenones F-M (1-8), together with two known derivatives, asperphenalenones E and B (9 and 10), were isolated from the axenic rice culture of this fungus. The structures of the new compounds were elucidated by nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism, and gas chromatography-mass spectrometry analyses. Asperphenalenones J-M (5-8) are unusual phenalenone adducts that are conjugated to diterpenoid glycosides. Asperphenalenones F and H showed moderate antibacterial activity against methicillin-resistant Staphylococcus aureus, with minimal inhibitory concentrations of 12.5 and 25 μM, respectively. Asperphenalenone B exhibited low antiviral activity against the human immunodeficiency virus replication. Furthermore, asperphenalenones F and H exhibited low cytotoxicity against Jurkat cells, while all other compounds were devoid of cytotoxicity.

Metabolites from Clonostachys Fungi and Their Biological Activities

Clonostachys (teleomorph: Bionectria) fungi are well known to produce a variety of secondary metabolites with various biological activities to show their pharmaceutical and agrochemical applications. Up to now, at least 229 secondary metabolites, mainly including 84 nitrogen-containing metabolites, 85 polyketides, 40 terpenoids, and 20 other metabolites, have been reported. Many of these compounds exhibit biological activities, such as cytotoxic, antimicrobial, antileishmanial, antimalarial activities. This mini-review aims to summarize the diversity of the secondary metabolites as well as their occurrences in Clonostachys fungi and biological activities.

Transcriptomic and Exometabolomic Profiling Reveals Antagonistic and Defensive Modes of Clonostachys rosea Action Against Fusarium graminearum

The mycoparasite Clonostachys rosea ACM941 is under development as a biocontrol organism against Fusarium graminearum, the causative agent of Fusarium head blight in cereals. To identify molecular factors associated with this interaction, the transcriptomic and exometabolomic profiles of C. rosea and F. graminearum GZ3639 were compared during coculture. Prior to physical contact, the antagonistic activity of C. rosea correlated with a response heavily dominated by upregulation of polyketide synthase gene clusters, consistent with the detected accumulation of corresponding secondary metabolite products. Similarly, prior to contact, trichothecene gene clusters were upregulated in F. graminearum, while those responsible for fusarielin and fusarin biosynthesis were downregulated, correlating with an accumulation of trichothecene products in the interaction zone over time. A concomitant increase in 15-acetyl deoxynivalenol-3-glucoside in the interaction zone was also detected, with C. rosea established as the source of this detoxified mycotoxin. After hyphal contact, C. rosea was found to predominantly transcribe genes encoding cell wall-degradation enzymes, major facilitator superfamily sugar transporters, anion:cation symporters, as well as alternative carbon source utilization pathways, together indicative of a transition to necrotropism at this stage. F. graminearum notably activated the transcription of phosphate starvation pathway signature genes at this time. Overall, a number of signature molecular mechanisms likely contributing to antagonistic activity by C. rosea against F. graminearum, as well as its mycotoxin tolerance, are identified in this report, yielding several new testable hypotheses toward understanding the basis of C. rosea as a biocontrol agent for continued agronomic development and application.

Functional analysis of polyketide synthase genes in the biocontrol fungus Clonostachys rosea

Clonostachys rosea is a mycoparasitic fungus used for biological control of plant diseases. Its genome contains 31 genes putatively encoding for polyketide synthases (PKSs), 75% of which are arranged in biosynthetic gene clusters. Gene expression analysis during C. rosea interactions with the fungal plant pathogens Botrytis cinerea and Fusarium graminearum showed common and species-specific induction of PKS genes. Our data showed a culture media dependent correlation between PKS gene expression and degree of antagonism in C. rosea. The pks22 and pks29 genes were highly induced during fungal-fungal interactions but not during pigmentation, and gene deletion studies revealed that PKS29 was required for full antagonism against B. cinerea, and for biocontrol of fusarium foot rot on barley. Metabolite analysis revealed that Δpks29 strains has a 50% reduced production (P = 0.001) of an unknown polyketide with molecular formula C₁₅H₂₈O₃, while Δpks22 strains lost the ability to produce four previously unknown polyketides named Clonorosein A-D. Clonorosein A and B were purified, their structures determined, and showed strong antifungal activity against B. cinerea and F. graminearum. These results show that PKS22 is required for production of antifungal polyketide Clonorosein A-D, and demonstrate the role of PKS29 in antagonism and biocontrol of fungal plant diseases.

Profiling of the Transcriptomic Responses of Clonostachys rosea Upon Treatment With Fusarium graminearum Secretome

Clonostachys rosea strain ACM941 is a fungal bio-control agent patented against the causative agent of Fusarium Head Blight, Fusarium graminearum. Although the molecular details remain enigmatic, previous studies have suggested that C. rosea may secrete F. graminearum growth inhibitors. Further toward this, experiments described herein show that induction of C. rosea cultures by the addition of an aliquot of F. graminearum(Fg)-spent media (including macroconidia), yield C. rosea (Cr)-spent media that elicited higher anti-F. graminearum activity than either control or deoxynivalenol (DON)-induced Cr-spent media. To gain additional insight into the genetic and metabolic factors modulating this interaction, transcriptomic (RNAseq) profiles of C. rosea in response to DON and Fg-spent media treatment, were developed. This analysis revealed 24,112 C. rosea unigenes, of which 5,605 and 6,285 were differentially regulated by DON and F-spent media, respectively. More than half of these unigenes were up-regulated, with annotations, most notably in the Fg-spent media treatment data, suggesting enhancement of polyketide (PK) and non-ribosomal peptide (NRP) secondary metabolite precursor synthesis, and PK/NRP-like synthases. Four ABC transporters were also up-regulated in response to Fg-spent media. Further analysis showed that the PK and NRP-like synthases belong to three gene clusters that also include ABC transporters, and other genes known to tailor secondary metabolite biosynthesis. The RNAseq data was further validated using quantitative RT-qPCR. Taken together, these results show that C. rosea responds to the presence of Fg-spent media (and to a lesser extent, DON-alone) by up-regulating unique aspects of its secondary metabolism-related genetic repertoire. The identities and roles of C. rosea secondary metabolites produced by the targeted gene clusters are now under investigation.

Necrotrophic Mycoparasites and Their Genomes

Mycoparasitism is a lifestyle where one fungus establishes parasitic interactions with other fungi. Species of the genus Trichoderma together with Clonostachys rosea are among the most studied fungal mycoparasites. They have wide host ranges comprising several plant pathogens and are used for biological control of plant diseases. Trichoderma as well as C. rosea mycoparasites efficiently overgrow and kill their fungal prey by using infection structures and by applying lytic enzymes and toxic metabolites. Most of our knowledge on the putative signals and signaling pathways involved in prey recognition and activation of the mycoparasitic response is derived from studies with Trichoderma. These fungi rely on G-protein signaling, the cAMP pathway, and mitogen-activated protein kinase cascades during growth and development as well as during mycoparasitism. The signals being recognized by the mycoparasite may include surface molecules and surface properties as well as secondary metabolites and other small molecules released from the prey. Their exact nature, however, remains elusive so far. Recent genomics-based studies of mycoparasitic fungi of the order Hypocreales, i.e., Trichoderma species, C. rosea, Tolypocladium ophioglossoides, and Escovopsis weberi, revealed not only several gene families with a mycoparasitism-related expansion of gene paralogue numbers, but also distinct differences between the different mycoparasites. We use this information to illustrate the biological principles and molecular basis of necrotrophic mycoparasitism and compare the mycoparasitic strategies of Trichoderma as a "model" mycoparasite with the behavior and special features of C. rosea, T. ophioglossoides, and E. weberi.