RESUMO
Aspergillus flavus is the second most common cause of aspergillosis infection in immunocompromised patients and is responsible for the production of aflatoxins. Little is known about the population structure of A. flavus, although recent molecular and phenotypic data seem to demonstrate that different genetic lineages exist within this species. The aim of this study was to carry out a morphological, physiological, and molecular analysis of a set of clinical and environmental isolates to determine whether this variability is due to species divergence or intraspecific diversity, and to assess whether the clinical isolates form a separate group. The amdS and omtA genes were more phylogenetically informative than the other tested genes and their combined analysis inferred three main clades, with no clear distinction between clinical and environmental isolates. No important morphological and physiological differences were found between the members of the different clades, with the exception of the assimilation of d-glucosamine, which differentiates the members of the clade II from the others.
Assuntos
Aspergilose/microbiologia , Aspergillus flavus/genética , Amidoidrolases/química , Amidoidrolases/genética , Aspergillus flavus/classificação , Aspergillus flavus/metabolismo , Aspergillus flavus/ultraestrutura , Sequência de Bases , DNA Fúngico/química , DNA Fúngico/genética , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Variação Genética , Metiltransferases/química , Metiltransferases/genética , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Alinhamento de Sequência , Microbiologia do SoloRESUMO
Aflatoxin B(1) (AFB(1)) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oil of Ageratum conyzoides, on the mycelial growth and aflatoxin B(1) production by Aspergillus flavus were studied. Cultures were incubated in yeast extract-sucrose (YES) broth for days at 25 degrees C at the following different concentrations of the essential oil (from 0.0 to 30mug/mL). The essential oil inhibited fungal growth to different extents depending on the concentration, and completely inhibited aflatoxin production at concentrations above 0.10microg/mL. The analysis of the oil by GC/MS showed that its main components are precocene II (46.35%), precocene I (42.78%), cumarine (5.01%) and Trans-caryophyllene (3.02%). Comparison by transmission electron microscopy of the fungal cells, control and those incubated with different concentrations of essential oil, showed ultra-structural changes which were concentration dependent of the essential oil of A. conyzoides. Such ultra-structural changes were more evident in the endomembrane system, affecting mainly the mitochondria. Degradation was also observed in both surrounding fibrils. The ability to inhibit aflatoxin production as a new biological activity of A.conyzoides L. indicates that it may be considered as a useful tool for a better understanding of the complex pathway of aflatoxin biosynthesis.
Assuntos
Aflatoxina B1/antagonistas & inibidores , Ageratum/química , Aspergillus flavus/efeitos dos fármacos , Óleos de Plantas/farmacologia , Aflatoxina B1/biossíntese , Aflatoxina B1/toxicidade , Antifúngicos/química , Antifúngicos/farmacologia , Aspergillus flavus/crescimento & desenvolvimento , Aspergillus flavus/metabolismo , Aspergillus flavus/ultraestrutura , Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Microscopia Eletrônica de Transmissão , Óleos de Plantas/químicaRESUMO
E relatado caso de nodulo solitario pulmonar por Scedosporium apiospermum (Pseudallescheria boydii). Foi feita uma revisao da literatura pertinente e, alem disso, casos com lesoes similares causadas por outros fungos oportunistas sao comentados