Caracterização bioquímica e molecular de Cryptococcus spp. isolados de excretas ambientais de pombos (Columba livia domestica) / Biochemical and molecular characterization of Cryptococcus spp. isolates from environmental feces of pigeons (Columba livia domestic)

Os pombos possuem uma rica diversidade de microrganismo, entre eles fungos sapróbios, como do gênero Cryptococcus, que podem atuar como agentes patogênicos para o homem e animais. Objetivou-se o isolamento, a caracterização bioquímica e a molecular de amostras de Cryptococcus spp. de excretas ambientas de pombos. Foram colhidas 100 amostras ambientais de pontos equidistantes e representativos da área da cidade de Araçatuba, São Paulo. As amostras foram rasteladas do solo de vias públicas, armazenadas em frasco coletor e encaminhadas para o Laboratório de Bacteriologia e Micologia da FMVA, onde foram processadas e cultivadas em duplicata, em placas de Petri contendo ágar Sabouraud dextrose a 4% e Niger. Em seguida, foram incubadas à temperatura ambiente e a 30ºC, respectivamente, por um período não inferior a 15 dias. Após a observação diária, as colônias sugestivas para levedura foram reisoladas em ágar Niger e submetidas a testes bioquímicos para posterior caracterização molecular pela técnica da PCR. Como resultado, a caracterização bioquímica e a molecular isolaram 32 colônias leveduriformes, sendo 8% dos cultivos positivos para Cryptococcus neoformans var. neoformans, 17% para Rhodotorula rubidae e 7% Candida albicans. Pelo exposto, concluiu-se que excretas ambientais de pombos constituem um microfoco para Cryptococcus neoformans var. neoformans e outras leveduras com potencial patogênico, representando um risco à saúde pública, sendo necessárias medidas preventivas, como a higienização com a correta remoção das excretas, a fim de minimizar os riscos de exposição ambiental.

Pigeons have a rich diversity of microrganisms, including fungi saprobes such as the genus Cryptococcus that can act as a pathogen for humans and animals. The aim of this was their isolation, biochemical and molecular characterization of samples of Cryptococcus from ambientas avian excreta. One hundred environmental samples,representative of the area equidistant from Araçatuba, São Paulo points were collected. The samples were removed and stored in collection bottles, sent to the Laboratory of Bacteriology and Mycology of FMVA, where they were processed and cultivated in duplicate on Petri dishes containing Sabouraud dextrose 4% and Niger and incubated at room temperature 30° C, respectively, for a period of no less than 15 days. Colonies after daily observation which were suggestive for yeast growth were re-isolated in Niger agar and subjected to biochemical analisis for further molecular characterization by PCR tests. As results, the biochemical and molecular characterization of 32 yeast colonies revealed 8% of cultures positive for Cryptococcus neoformans var. neoformans, 17% Rhodotorula rubidae and 7% Candida albicans. It was concluded that environmental avian excreta are active sites for replication of Cryptococcus neoformans var. neoformans and other yeasts with pathogenic potential. These constitute a public health risk, and preventive measures are necessary, such as cleaning and complete removal of excreta in order to minimize the risk of environmental exposure.

Silver nanoparticle production by the fungus Fusarium oxysporum: nanoparticle characterisation and analysis of antifungal activity against pathogenic yeasts

The microbial synthesis of nanoparticles is a green chemistry approach that combines nanotechnology and microbial biotechnology. The aim of this study was to obtain silver nanoparticles (SNPs) using aqueous extract from the filamentous fungus Fusarium oxysporum as an alternative to chemical procedures and to evaluate its antifungal activity. SNPs production increased in a concentration-dependent way up to 1 mM silver nitrate until 30 days of reaction. Monodispersed and spherical SNPs were predominantly produced. After 60 days, it was possible to observe degenerated SNPs with in additional needle morphology. The SNPs showed a high antifungal activity against Candida and Cryptococcus , with minimum inhibitory concentration values ≤ 1.68 µg/mL for both genera. Morphological alterations of Cryptococcus neoformans treated with SNPs were observed such as disruption of the cell wall and cytoplasmic membrane and lost of the cytoplasm content. This work revealed that SNPs can be easily produced by F. oxysporum aqueous extracts and may be a feasible, low-cost, environmentally friendly method for generating stable and uniformly sized SNPs. Finally, we have demonstrated that these SNPs are active against pathogenic fungi, such as Candida and Cryptococcus .