ABSTRACT
The distribution of Aspergillus species in soil has been widely studied all over the world. The aim of this study was the phenotypic and genotypic characterization of species belonging to section Fumigati present in soils from two Argentinian semi-desert areas having different geological conditions. Altogether, 23 isolates belonging to Aspergillus section Fumigati were recovered and identified using a polyphasic approach including phenotypic and molecular identifications. Aspergillus fumigatus sensu stricto and Aspergillus fumigatiaffinis had the highest frequency, of occurrence while isolates closely related to Aspergillus udagawae and Aspergillus felis were rarely observed. A. fumigatiaffinis and isolates closer to A. udagawae were isolated for the first time from Argentinian soils and this is the first report on the occurrence of species belonging to the A. felis clade in South America. Recent scientific interests in biodiversity, as well as the increasing importance of aspergilli as causative agents of human and animal diseases increase the need to understand the diversity and occurrence of these fungi in nature.
La distribución de especies de Aspergillus en el suelo se ha estudiado ampliamente en todo el mundo. El objetivo de este trabajo fue caracterizar fenotípica y genotípicamente las especies pertenecientes a la sección Fumigati presentes en los suelos de dos zonas semidesérticas de Argentina con diferentes geologías. En total, 23 Aspergillus de la sección Fumigati fueron aislados e identificados utilizando un enfoque polifásico incluyendo identificaciones fenotípicas y moleculares. Aspergillus fumigatus sensu stricto y Aspergillus fumigatiaffinis aparecieron con mayor frecuencia, mientras que los aislamientos relacionados a Aspergillus udagawae y a Aspergillus felis se observaron raramente. Este es el primer informe de A. fumigatiaffinis y de aislamientos estrechamente relacionados a A. udagawae en suelos argentinos; también el primero sobre la ocurrencia de especies pertenecientes al clado A. felis en Sudamérica. El emergente interés científico en la biodiversidad, así como la creciente importancia de Aspergillus como agentes causales de enfermedades humanas y animales, aumentan la necesidad de conocer la diversidad y la ocurrencia de estos hongos en la naturaleza.
Subject(s)
Aspergillus , Soil Microbiology , Biodiversity , Argentina , Aspergillus/isolation & purification , South AmericaABSTRACT
Fungi of the genus Paracoccidioides are responsible for paracoccidioidomycosis. The occurrence of drug toxicity and relapse in this disease justify the development of new antifungal agents. Compounds extracted from fungal extract have showing antifungal activity. Extracts of 78 fungi isolated from rocks of the Atacama Desert were tested in a microdilution assay against Paracoccidioides brasiliensis Pb18. Approximately 18% (5) of the extracts showed minimum inhibitory concentration (MIC) values≤ 125.0 µg/mL. Among these, extract from the fungus UFMGCB 8030 demonstrated the best results, with an MIC of 15.6 µg/mL. This isolate was identified as Aspergillus felis (by macro and micromorphologies, and internal transcribed spacer, β-tubulin, and ribosomal polymerase II gene analyses) and was grown in five different culture media and extracted with various solvents to optimise its antifungal activity. Potato dextrose agar culture and dichloromethane extraction resulted in an MIC of 1.9 µg/mL against P. brasiliensis and did not show cytotoxicity at the concentrations tested in normal mammalian cell (Vero). This extract was subjected to bioassay-guided fractionation using analytical C18RP-high-performance liquid chromatography (HPLC) and an antifungal assay using P. brasiliensis. Analysis of the active fractions by HPLC-high resolution mass spectrometry allowed us to identify the antifungal agents present in the A. felis extracts cytochalasins. These results reveal the potential of A. felis as a producer of bioactive compounds with antifungal activity.