Production and analysis of ochratoxin A produced by Aspergillus ochraceus ITEM 5137 in submerged culture (original) (raw)
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Immunochemical detection of ochratoxin A in black Aspergillus strains
Mycopathologia, 1996
One hundred and fifty-seven strains belonging to Aspergillus section Nigri were tested for ochratoxin A production using three different methods: a relatively new immunochemical method based on an enzyme-linked immunosorbent assay (ELISA), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The monoclonal antibody-based ELISA technique was successfully used to screen for low levels of ochratoxin A in the black Aspergilli without concentrating the culture filtrates. The results were confirmed by TLC and HPLC analysis and chemical derivatization. These latter methods required concentrated filtrates. Ochratoxin A was detected in the culture filtrates of five of the 12 A. carbonarius strains, none of the 45 A.japonicus strains and three of the 100 isolates in the A. niger aggregate (A. foetidus, A. awamori and A. niger).
Mycotoxin Research, 1995
The toxicity of ochratoxin A (OTA), a mycotoxin produced by fungi of Aspergillus or Penicillium genera Is now well documented. Its nephrotoxicity, Immunosuppression, teratogenicity, and carcinogenicity have been widely studied. Physical and biochemical methods have been studied to prevent these toxlnogenlc Aspergillus and Penicillium from producing OTA,and/or to destroy the mycotoxin when already produced In a liquid or a solid medium. Repeated freezing at-20• C and thawing at + 26• C aleatory reduce OTA production In a liquid medium. Exposure to UV B for different periods of time Is efficient In preventing OTA production In a liquid medium. Gamma-Irradiation from 2 to 5 kGy gives good results In preventing the production of OTAor destroying It when already produced. Carboxypeptidase Is very efficient at 5 units/50 ml In a liquid medium for cleaving the OTA already produced.
Mycotoxin Research, 2013
This study determined the biotic interaction between 30 non-toxigenic indigenous strains of Aspergillus niger aggregate, Aspergillus flavus, Trichoderma spp., Mucor spp., Cladosporium spp., Ulocladium spp., Curvularia spp., Absidia spp., Geotrichum spp. and Acremonium spp., isolated from soil destined for maize crops, with respect to their ability to prevent ochratoxin A (OTA) production by A. carbonarius on "in vitro" assay, on liquid and solid medium. OTA production was completely inhibited when A. carbonarius was inoculated in a interactive mixed culture with all A. niger aggregate strains assayed, a 80 % of Trichoderma spp. strains, a 40 % of Cladosporium spp. strains, Acremonium spp and Geotrichum spp; only one strain of A. flavus tested was able to completely inhibit the mycotoxin accumulation. OTA production increased when A. carbonarius ACS 8 was growing on liquid interactive mixed culture with Mucor spp strains. These results demonstrated that OTA production by Aspergillua carbonarius strain was significantly influenced by the presence of different non-toxigenic fungal strains when growing together on paired cultures. Keywords Aspergillus carbonarius. Indigenous mycobiota. Ochratoxin A. Interacting mixed cultures Fusarium , Penicillum , Trichoderma, Cladosporium and Alternaria (González et al. 1995). Throughout the world, maize and maize derivatives are frequently contaminated with a family of mycotoxins such as ochratoxins and ochratoxigenic fungi (Caldas et al. 2002; Magnoli et al. 2006a; Rosa et al. 2006; Fraga et al. 2007). In Argentina, Aspergillus carbonarius , A. niger aggregate species and uniseriates Aspegillus species such as A. aculeatus and A. japonicus have frequently been isolated from several agricultural products, e.g., coffee beans, red wine, dried vine fruits, maize and peanut kernels, and feeds (
Assessment of the ochratoxin A production ability of Aspergillus tubingensis
Food Additives & Contaminants: Part A, 2012
Black aspergilli are among the predominant fungal contaminants in herbal teas. Despite the ability of some species in this group to produce the mycotoxins ochratoxin A (OTA) and fumonisins no study had been done to investigate in detail their presence in this commodity. In the present work conventional herbal teas available on the Swiss market were investigated for black aspergilli contamination. Black aspergilli were found in 16 of 22 samples, ranging from 10 to 3500 colony forming units per gram of herbal tea. Recovered isolates were identified to the species level by calmodulin sequencing. The most frequently isolated species were Aspergillus niger, Aspergillus acidus, Aspergillus awamori and Aspergillus tubingensis. Aspergillus carbonarius, the most important OTA-producing black Aspergillus, could not be recovered. A. niger and A. awamori isolates were tested for their ability to produce fumonisins and OTA in vitro. Fumonisins were produced by 76% of A. niger and 37% of A. awamori isolates. 7% of A. niger and none A. awamori isolates could produce OTA. In total, 12 of 22 samples were found to be contaminated with black aspergilli able to produce major mycotoxins. Our results indicate that mycotoxins producing black aspergilli are widespread fungal contaminants of herbal teas. Therefore, their presence as well as the occurrence of their mycotoxins should be further investigated to assess health risks linked with the consumption of this commodity.
Food Microbiology, 2006
Aspergillus ochraceus is an important contaminant of diverse substrates, such as cereals, coffee, grapes and derivates. This fungus produce a nephrotoxic metabolite, ochratoxin A (OTA), whose presence on food and feeds may be an important risk for animal and human health. The aim of this work was to evaluate the significance of the origin of A. ochraceus isolates on their OTA production patterns on different substrates (yeast extract sucrose (YES) broth, irradiated barley grains, irradiated green coffee beans and sterilized grapes) and under different environmental conditions. Results did not show a significant influence of the isolation source on OTA-production profiles by A. ochraceus isolates on several substrates, since the isolates which produced the highest OTA amounts in vitro (YES medium) were also the isolates with the highest OTA yields on the other substrates. Abiotic factors assayed (water activity, temperature and substrate) affected significantly OTA productions by A. ochraceus. Maximum OTA amounts were detected at 25 1C and 0.98 a w on all substrates tested. The highest OTA accumulations found on the different substrates were: green coffee beans (4 2 mg g À1), barley grains ($1 mg g À1), YES medium (13.9 mg ml À1) and grape ($3 ng g À1).
Food Microbiology, 2006
The effect of water activity (a w) (0.78-0.99) and temperature (15 and 30 1C) on growth and production of ochratoxin A (OTA) of six Aspergillus carbonarius strains was studied in two culture media: Czapek yeast autolysate (CYA) agar and yeast extract sucrose (YES) agar, during a period of 30 days. The strains were selected to include different sources and different reported abilities to produce OTA and were characterized by RAPD and ITS-5.8S rDNA sequencing. CYA showed to be better culture medium than YES for OTA production in the isolates tested. OTA concentration was higher at 15 1C than at 30 1C. At 30 1C, ranges for OTA production were more restrictive than those for growth. OTA was produced from 0.86, 0.90 or 0.94 a w depending on the strain. At 15 1C, growth and OTA production were detected only in the 0.94-0.99 a w range. The molecular study performed showed that five of the strains were conspecific and no correlation was found between molecular data and the OTA production level or origin. The remaining strain had never been able to produce OTA and will probably represent a new species in the Aspergillus section Nigri. Our results show that A. carbonarius is able to grow and produce OTA in a wide range of water activities at both high and low temperatures.
An easy screening method for fungi producing ochratoxin A in pure culture
International Journal of Food Microbiology, 2001
A simple screening method has been developed for detecting ochratoxin production by fungi, based on high-performance liquid chromatographic determinations on extracts obtained from agar plugs cut from pure Petri dish cultures. Two culture Ž media, Yeast Extract Sucrose agar and Czapek Yeast Extract agar, and three extraction solvents methanol, methylene. chloriderformic acid, and methanolrformic acid were compared. All of the isolates tested produced ochratoxin A in one or both culture media after 7 or 14 days of incubation. Based on the results obtained, the use of both culture media is recommended. As extraction solvent, either methanol or methanol-formic acid could be used. This method also provides quantitative information on the level of ochratoxin produced by the cultures. The simplicity of the method makes it very useful when many fungal isolates need to be screened.
Degradation of ochratoxin A by Aspergillus species
International Journal of Food Microbiology, 2000
Mycotoxin contamination of agricultural products is a serious health hazard throughout the world. Besides attempts to eliminate mycotoxins from contaminated substrates by physical and chemical methods, the ability of microbes to degrade mycotoxins is now being widely examined. In this study, several Aspergillus species were examined for their ability to degrade ochratoxin A. A. fumigatus and black Aspergillus strains were found to detoxify ochratoxin A in culture media. The kinetics of ochratoxin A detoxification by an atoxigenic A. niger strain was examined by thin layer chromatography, high-performance liquid chromatography and an immunochemical technique. A. niger CBS 120.49 was found to effectively eliminate ochratoxin A from both liquid and solid media, and the degradation product, ochratoxin a, was also decomposed.