RESUMEN
From an endophytic strain of Gliocladium sp. isolated from the Amazonian plant Strychnos cf. toxifera, we obtained the diketopiperazine alkaloid cyclo-(glycyl-L-tyrosyl)-4,4-dimethylallyl ether (1), the steroids ergosterol (2), ergosterol peroxide (3), cerevisterol (4) and the citric acid (5). The AcOEt extract of the fermented broth by Gliocladium sp. showed potent activity against the cancer cell lines MDA-MB435 (human breast cancer cells), HCT-8 (human colorectal cancer cells) and SF-295 (human glioblastoma cancer cells). Compound 1 exhibited a strong antimicrobial activity against Micrococcus luteus at a concentration of 43.4 µM.
Asunto(s)
Alcaloides/química , Alcaloides/farmacología , Antiinfecciosos/química , Antiinfecciosos/farmacología , Dicetopiperazinas/química , Gliocladium/química , Strychnos/microbiología , Alcaloides/aislamiento & purificación , Antineoplásicos/farmacología , Línea Celular Tumoral/efectos de los fármacos , Ácido Cítrico/aislamiento & purificación , Dicetopiperazinas/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Endófitos/química , Ergosterol/análogos & derivados , Ergosterol/aislamiento & purificación , Gliocladium/aislamiento & purificación , Humanos , Pruebas de Sensibilidad Microbiana , Micrococcus luteus/efectos de los fármacos , Estructura Molecular , Péptidos Cíclicos/química , Péptidos Cíclicos/aislamiento & purificación , Fitosteroles/aislamiento & purificaciónRESUMEN
To aid the development of compatible biocontrol inocula, a prescreening method for the prediction of compatibility of fungal antagonists was developed. Compatibility between 18 Clonostachys isolates with known antagonistic capabilities against Phytophthora palmivora was tested using intra- or interisolate pairings (dual cultures) on water agar plates, a hyphal interaction experiment and a modified double host-range experiment. Almost all inter- or intraisolate pairings of Clonostachys isolates showed growth inhibition zones and did not show free hyphal intermingling. A hyphal interaction experiment on water agar demonstrated that the aggressiveness of a Clonostachys isolate and its susceptibility to mycoparasitism were unrelated phenomena. However the level of aggressiveness and/or susceptibility of an isolate were largely dependant on the isolate with which it was challenged. The degree of growth-inhibition caused by an isolate was unrelated to the hyphal damaged it caused or received. In the double host-range experiment all possible pairs from four Clonostachys isolates were inoculated in different ratios (10 000-fold range) on plates precolonized with one of two P. palmivora isolates. The results showed that antagonistic capabilities of certain combinations were affected by the Clonostachys isolates. The primary host, P. palmivora, did not affect antagonistic capabilities; whereas inoculum ratio did. Of note, it was not possible to predict the outcome of the double host range on the basis of the results of the hyphal interaction experiment. In conclusion the competitive abilities of Clonostachys isolates depend on the partner with which they are applied and less on resource availability. The double host-range test as developed here might provide the most representative tool to date to test compatibility of fungal antagonists to be used in biocontrol inocula. However the link between the results of the double host-range test and field efficacy of biocontrol inocula remains to be investigated.
Asunto(s)
Gliocladium/fisiología , Phytophthora/crecimiento & desarrollo , Gliocladium/aislamiento & purificación , Gliocladium/patogenicidad , Hifa/fisiología , Control Biológico de Vectores/métodos , Phytophthora/aislamiento & purificación , Phytophthora/patogenicidadRESUMEN
Soil biodiversity plays a key role in the sustainability of agriculture systems and indicates the level of health of soil, especially when considering the richness of microorganisms that are involved in biological control of soilborne diseases. Cultural practices may produce changes in soil microflora, which can be quantified through the isolation of target microorganisms. Rhizosphere soil samples were taken from an assay with different crop rotations and tillage systems, and populations of Trichoderma spp., Gliocladium spp. and actinomycetes were quantified in order to select the general and selective culture media that better reflect the changes of these microbial populations in soil. The most efficient medium for the isolation of Trichoderma spp. and Gliocladium spp. was potato dextrose agar modified by the addition of chloramphenicol, streptomycin and rose bengal, and for actinomycetes was Küster medium, with cycloheximide and sodium propionate.