Biological Control of Rhizoctonia solani AG1-1A, the Causal Agent of Rice Sheath Blight with Trichoderma Strains

Sheath blight caused by Rhizoctonia solani is one of the most serious rice diseases worldwide. The disease is currently managed only by the excessive application of chemical fungicides which are toxic and not environmentally friendly. Therefore, greater emphasis should be given to biological control as being both safe and effective. Trichoderma species are ubiquitous fungi in the soil and have an antagonistic activity against several soil-borne plant pathogens including R. solani. The present study was undertaken to evaluate the potential of indigenous Trichoderma strains from Mazandaran province, Northern Iran (a Mediterranean region on the southern coast of the Caspian Sea) against R. solani AG1-IA  in vitro, and against sheath blight disease in the glasshouse, in order to find biocontrol isolates for application in the field. More than 200 Trichoderma strains were isolated from the soil, plant debris and the phyllosphere in rice felds. Strains were first screened for their antagonism to R. solani by in vitro antagonism tests including dual culture, antibiosis, the effect of Trichoderma strains on the production and viability of R. solani sclerotia, and hyperparasitism on microscopic slides. According to the in vitro experiments, several strains belonging to T. harzianum, T. virens and T. atroviride showed excellent biocontrol. These potential antagonist strains were further evaluated for their effectiveness in controlling sheath blight under glasshouse conditions. Among the 55 selected strains, seven significantly controlled the disease. T. harzianum AS12-2 was the most effective strain in controlling rice sheath blight, better even than propiconazole, the most commonly used fungicide in Iran

Vapor as a carrier of toxicity in a health troubled building

Penicillium expansum was identified as a major contaminant in indoor air, settled dust and materials of several buildings connected to indoor air related health complaints. This fungus emitted large quantities of exudates when cultivated on laboratory media. The exudates proved toxic towards four different mammalian test cells up to 10000 fold dilution. Toxins identified by LC-MS/MS were communesins and chaetoglobosin. Air dispersal of the toxic exudates was investigated with an experimental set-up where natural convection was generated by temperature gradient. It was found that the exudate with the contained toxins became airborne transported from the warmer surface to the colder surface. The results thus demonstrate transportation of microbially produced toxic substances across the air space. The role of liquid emissions from indoor molds represents a novel mechanism for human exposure in mold contaminated buildings. In this paper we report that vapor condensed from the indoor air of building affected with molds Aspergillus versicolor, Aspergillus calidoustus and Penicillium expansum contained substances that were acutely toxic when exposed to mammalian cells in vitro. The results encourage further study of condensed indoor water vapor as a tool to assess the presence of airborne substances with possible adverse health effects

Old dry mold growth seems to emit less bioactive metabolites and surfactants than actively growing microbes

We characterized the toxicity and surfactant properties of old and fresh biomasses of indoor isolates of Trichoderma atroviride,Aspergillus versicolor, Chaetomium sp., Stachybotrys sp. and Rhizopus sp. Toxicity of cell dispersals fromold dry biomasses (> 12 months old) and actively growing molds(< 3 weeks old) was tested as inhibition of proliferation with somatic mammalian cell lines(PK-15 and MNA).Fresh biomasses were up to 100 times more toxic than old dry biomasses. When calculated per conidial particle,100 times more toxicity was associated with the fresh conidia than the old ones.Surfactant activity was detected both in biomass dispersals and exudates. We hypotized that the metabolic state of the fungal growth may influence fungal metabolite emission into indoor air. This information may be important when mouldy buildings are renovated.Peer reviewe

Invasive Trichoderma spp. infections: clinical presentation and outcome of cases from the literature and the FungiScope(R) registry

Background Trichoderma spp. are filamentous fungi causing invasive fungal diseases in patients with haematological malignancies and in peritoneal dialysis patients. Objectives To analyse clinical presentation, predisposing factors, treatment and outcome of Trichoderma infections. Methods A systematic literature review was conducted for published cases of invasive Trichoderma infection in PubMed until December 2021 and by reviewing the included studies' references. Cases from the FungiScope(R) registry were added to a combined analysis. Results We identified 50 invasive infections due to Trichoderma species, including 11 in the FungiScope(R) registry. The main underlying conditions were haematological malignancies in 19 and continuous ambulatory peritoneal dialysis (CAPD) in 10 cases. The most prevalent infection sites were lung (42%) and peritoneum (22%). Systemic antifungal therapy was administered in 42 cases (84%), mostly amphotericin B (n = 27, lipid-based formulation 13/27) and voriconazole in 15 cases (30%). Surgical interventions were performed in 13 cases (26%). Overall mortality was 48% (n = 24) and highest for allogeneic HSCT and solid organ transplantation (SOT) recipients [80% (4/5) and 77% (7/9), respectively]. In patients treated with amphotericin B, voriconazole and caspofungin, mortality was 55% (15/27), 46% (7/15) and 28% (2/7), respectively. Three out of four patients treated with a combination therapy of voriconazole and caspofungin survived. Conclusions Despite treatment with antifungal therapies and surgery, invasive Trichoderma infections are life-threatening complications in immunocompromised patients, especially after HSCT and SOT. In addition, Trichoderma spp. mainly affect the lungs in patients with haematological malignancies and the peritoneum in CAPD patients