Mycobiota and aflatoxin B1 contamination of rainbow trout (Oncorhinchus mykiss) feed with emphasis to Aspergillus section Flavi

In the present study, mycobiota and natural occurrence of aflatoxin B1 (AFB1) in pellet feed and feed ingredients used in a feed manufacturing plant for rainbow trout nutrition was investigated. The samples were cultured on the standard isolation media for 2 weeks at 28 ºC. Identification of fungal isolates was implemented based on the macro- and microscopic morphological criteria. AFB1 was detected using high performance liquid chromatography (HPLC). Based on the results obtained, a total of 109 fungal isolates were identified of which Aspergillus was the prominent genus (57.0%), followed by Penicillium (12.84%), Absidia (11.01%) and Pseudallscheria (10.10%). The most frequent Aspergillus species was A. flavus (60.66%) isolated from all feed ingredients as well as pellet feed. Among 37 A. flavus isolates, 19 (51.35%) were able to produce AFB1 on YES broth in the range of 10.2 to 612.8 µg/g fungal dry weight. HPLC analysis of trout feed showed that pellet feed and all feed ingredients tested except gluten were contaminated with different levels of AFB1 in the range of 1.83 to 67.35 µg/kg. Unacceptable levels of AFB1 were reported for feed including soybean, fish meal and wheat. These results indicate the importance of AF contamination of trout feed in amounts higher than the acceptable level as a risk factor for fish farming production

Use of a polyphasic approach including MALDI-TOF MS for identification of Aspergillus section Flavi strains isolated from food commodities in Brazil

Brazil is one the largest producers and exporters of food commodities in the world. The evaluation of fungi capable of spoilage and the production mycotoxins in these commodities is an important issue that can be of help in bioeconomic development. The present work aimed to identify fungi of the genus Aspergillus section Flavi isolated from different food commodities in Brazil. Thirty-five fungal isolates belonging to the section Flavi were identified and characterised. Different classic phenotypic and genotypic methodologies were used, as well as a novel approach based on proteomic profiles produced by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). Type or reference strains for each taxonomic group were included in this study. Three isolates that presented discordant identification patterns were further analysed using the internal transcribed spacer (ITS) region and calmodulin gene sequences. The data obtained from the phenotypic and spectral analyses divide the isolates into three groups, corresponding to taxa closely related to Aspergillus flavus, Aspergillus parasiticus, and Aspergillus tamarii. Final polyphasic fungal identification was achieved by joining data from molecular analyses, classical morphology, and biochemical and proteomic profiles generated by MALDI-TOF MS.Acknowledgments are due to FAPEMIG - Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (Brazil) for financial support. F. C. da Silva extends thanks to CAPES - Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (Brazil) for the PhD grant. C. Santos and N. Lima thank CAPES for the financial support as international visiting professors in the Post-Graduate Programme in Agricultural Microbiology, Federal University of Lavras, Lavras (MG), Brazil

Natural occurrence of T-2 toxin in domestic and imported rice

Abstract Background: Rice is one of the crops, which are prone to be contaminated with toxigenic fungi and their mycotoxins. This study aimed to investigate the natural occurrence of T-2 toxin in domestic and imported rice in Iran. Methods: In a cross-sectional descriptive study in winter 2007, 140 samples of imported rice (125 samples of Thai and 25 samples of Pakistani rice) and 60 samples of Iranian rice were collected from warehouses of canteens of governmental offices in Tehran. After grinding and methanol extraction of the rice samples, the amount of T-2 toxin was measured using a sandwich ELISA. INSTATA statistical software was used for data analysis. Results: All samples of rice were more or less contaminated with T-2 toxin but the amount did not exceed the permissible limit. Mean contamination of domestic and imported rice was 11.2±2.3 and 13±2.7 µg/kg, respectively. Regarding imported rice, mean of contamination was 14.5±4.6 µg/kg for the Pakistani rice and 12.6±2.2 µg/kg for the Thai rice. There was no significant difference between domestic and imported rice, nor did we find a meaningful difference among Iranian, Pakistani and Thai rice regarding the amount of contamination (P= 0.2). Conclusion: Although the amount of contamination is less than the safe limit, the extent of natural occurrence of T-2 toxin in rice in Iran indicates that contamination occurs somewhere in the production process. This, in turn, necessitates screening of rice for contamination with mycotoxins from farm to table

Application of PCR-RFLP to Rapid Identification of the Main Pathogenic Dermatophytes from Clinical Specimens

"nBackground: In the present study, a PCR-RFLP based molecular technique was designed to rapid identification of der­matophytes in clinical specimens. Skin scrapings obtained from human cases suspected to dermatophytosis were studied in or­der to identify involved etiological fungi."nMethods: In this experimental study, the specimens (skin scrapings) of patients referred to Mycology Department of Pas­teur Institute of Iran were inoculated on Petri dishes contained selective agar for pathogenic fungi (SAPF) and incubated at 25º C until visible growth of fungal colonies. The colonies were examined for standard morphological characteristics after visi­ble growth on the agar medium. A small portion of each fungal colony was further studied by restriction fragment length poly­morphism (RFLP) analysis of the PCR-amplified internal transcribed spacer (ITS) region of ribosomal DNA (rDNA). PCR amplicons were electrophoresed on 2% agarose gel after digesting by different restriction enzymes including MvaI, HinfI and HaeIII."nResults: Among 160 clinical samples examined, 6 dermatophyte species including  Trichophyton mentagrophytes, T. ru­brum, T. verrucosum, T. tonsurans, Microsporum canis and Epidermophyton floccosum were finally identified based on the col­ony morphology and microscopic criteria. Specific PCR products and RFLP patterns for MvaI, HinfI and HaeIII en­zymes allowed the rapid identification and reliable differentiation of isolated dermatophytes at the genus or species level for 5-10 day-old colonies."nConclusions: The results showed that PCR-RFLP analysis of the ITS region of rDNA is a rapid and reliable tool which al­lows identification of major pathogenic dermatophytes isolated in this study at species level in young 5-10 day-old colonies. &nbsp