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Virulence Potential of Aspergillus flavus Isolated from Dogs volume (12), special issue(1):232-238

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Aspergillus, Penicillium and Talaromyces species are frequently cited as contaminants of various substrata and are often associated with indoor environments. The main purpose of this study was to assess the potential pathogenicity of aerosol-derived fungi from Aspergillus, Penicillium and Talaromyces genera, isolated in the rooms for con­servation of cultural heritage artefacts, via estimating hemolytic activity. Hemolysis was detected in 20.58% of tested isolates at 37°C (11.76% partial and 8.82% complete) and 64.71% at 25°C (38.24% partial and 26.47% complete). The majority of isolates that caused α hemolysis led to the significant oxidation of hemoglobin iron with methemoglobin content in blood agar medium, higher than 80%. Aspergillus melleus was the only tested fungi that caused formation of ferry hemoglobin after the incubation at 25°C. Obtained I values (index of activity for hemolytic exoenzymes) for α hemolysis were in range of from 0.13 to 0.60 for 37°C, while for the temperature of 25°C values were in range of from 0.08 to 0.50. The same values for β hemolysis were in range of from 0.03 to 0.08 (37°C), i.e. 0.06 to 0.49 (25°C). Monitoring of pathogenic airborne fungi in indoor environments and estimation of their virulence is essential for the adequate assessment of human health risks.
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Pathogenesis of Aspergillus flavus on important agricultural products is a key concern on human health due to the synthesis and secretion of the hazardous secondary metabolite, aflatoxin. This study identified and further characterized aflatoxigenic A. flavus from groundnuts sampled from sundry shops in Kenya using integrated morphological and molecular approaches. The groundnuts were plated on potato dextrose agar for isolation and morphological observation of A. flavus based on macroscopic and microscopic features. Molecular characterization was done through amplification and comparison of the partial sequence of the ITS1-5.8S-ITS2 region. The expression analysis of aflR, aflS, aflD, aflP, and aflQ genes in the aflatoxin biosynthesis pathways was conducted to confirm the positive identification of A. flavus. The gene expression also aided to delineate toxigenic isolates of A. flavus from atoxigenic ones. Morphologically, 18 isolates suspected to be A. flavus were identified. Out of these, 14 isolates successfully amplified the 500 bp ITS region of A. flavus or Aspergillus oryzae, while 4 isolates were not amplified. All the remaining 14 isolates expressed at least one of the aflatoxigenic genes but only 5 had all the genes expressed. Partial sequencing revealed that isolates 5, 11, 12, 13, and 15 had 99.2%, 97.6%, 98.4%, 97.5%, and 100% homology, respectively, to the A. flavus isolate LUOHE, ITS-5.8S-ITS2, obtained from the NCBI database. The five isolates were accurate identification of atoxigenic A. flavus. Precise identification of toxigenic strains of A. flavus will be useful in establishing control strategies of the fungus in food products.
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Abstract From the aerial part of Salsala rasmarinus (Bunge ex Boiss) Eig. (Chenopodiaceae) and Adiantum capillus-veneris L. (Polypodiaceae) antimicrobial activity was detected. This is the first report on antimicrobial flavonoids from these species.
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The presence of yeasts on the hands of 86 healthy hosts (62 hospital workers and 24 healthy members of the community with no hospital exposure) was investigated. A high rate of colonization was found (59.3%). Candida parapsilosis was the most frequently isolated species (51%), independent of the origin of the samples. The potential virulence and resistance to antifungals of the 26 C. parapsilosis isolates were determined. All were proteinase producers and formed biofilms. The haemolytic activity was variable, with a predominance of total haemolysis of sheep erythrocytes. All isolates were susceptible to amphotericin B but two showed reduced susceptibility to fluconazole. Healthy people may be colonized by a species of yeast with a high capacity for adhesion to plastic surfaces, providing an infection risk to susceptible individuals.
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Species of Aspergillus section Flavi were isolated and identified in maize samples collected from a wide geographical region in northeastern China. Aspergillus flavus was identified to be the primary species in the population (99%) becoming a potential source of aflatoxin contamination in the region. Isolated A. flavus strains were classified into the S and L strains respectively based on their sclerotia morphology. Among the A. flavus strains identified, L strains dominated over the S strains in the maize samples studied. Both uniseriate and biseriate forms were observed in A. flavus L strain isolates. However, only uniseriate was observed in A. flavus S strain isolates. Microscopic characteristics of L and S strains were observed and reported. Some geographical differences between northeastern China and other countries and regions were discussed. This is the first study on the population dynamics of A. flavus versus A. parasiticus and the L and S strains within A. flavus in maize samples in northeastern China.
Veterinary and medical mycology. Directorate of Information and Publications of Agriculture, Indian Council of Agricultural Research ISBN
  • M Pal
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