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Huang JQ, Jiang HF, Zhou YQ, Lei Y, Wang SY, Liao BS. Ethylene inhibited aflatoxin biosynthesis is due to oxidative stress alleviation and related to glutathione redox state changes in Aspergillus flavus. Int J Food Microbiol 2009; 130:17-21. [DOI: 10.1016/j.ijfoodmicro.2008.12.027] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 12/10/2008] [Accepted: 12/20/2008] [Indexed: 11/26/2022]
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52
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Degola F, Berni E, Spotti E, Ferrero I, Restivo F. Facing the problem of “false positives”: Re-assessment and improvement of a multiplex RT-PCR procedure for the diagnosis of A. flavus mycotoxin producers. Int J Food Microbiol 2009; 129:300-5. [DOI: 10.1016/j.ijfoodmicro.2008.12.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 11/21/2008] [Accepted: 12/12/2008] [Indexed: 10/21/2022]
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53
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Rodrigues P, Venâncio A, Kozakiewicz Z, Lima N. A polyphasic approach to the identification of aflatoxigenic and non-aflatoxigenic strains of Aspergillus Section Flavi isolated from Portuguese almonds. Int J Food Microbiol 2008; 129:187-93. [PMID: 19110333 DOI: 10.1016/j.ijfoodmicro.2008.11.023] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 11/17/2008] [Accepted: 11/18/2008] [Indexed: 11/19/2022]
Abstract
A polyphasic approach consisting of morphological, chemical and molecular characterization was applied to 31 isolates of Aspergillus Section Flavi originating from Portuguese almonds, with the aim of characterizing and identifying aflatoxigenic and non-aflatoxigenic strains. On the basis of morphological characters (mainly colony color on Czapek-Dox agar and conidia morphology), we found two distinct groups among the population under study: 18 isolates (58%) had dark-green colonies and rough conidia, and were classified as Aspergillus parasiticus; the remaining 13 isolates (42%) had yellow-green colonies and smooth to finely rough globose conidia, and were classified as Aspergillus flavus. Chemical characterization involved the screening of the isolates for aflatoxins B (AFB) and G (AFG), and also for cyclopiazonic acid (CPA), by HPLC with fluorescence and UV detection, respectively. All A. parasiticus isolates were strong AFB and AFG producers, but no CPA production was detected, showing a consistent mycotoxigenic pattern. The A. flavus isolates showed to be more diversified, with 77% being atoxigenic, whereas 15% produced CPA and low levels of AFB and 8% produced the 3 groups of mycotoxins. Aflatoxin production was also screened on Coconut Agar Medium (CAM), and the results were consistent with the HPLC analysis. Sclerotia production showed no correlation to aflatoxigenicity. Molecularly, two genes of the aflatoxin biosynthetic pathway, aflD (=nor1) and aflQ (=ord1=ordA) were tested for presence and expression (by PCR and RT-PCR, respectively). The presence of both genes did not correlate with aflatoxigenicity. aflD expression was not considered a good marker for differentiating aflatoxigenic from non-aflatoxigenic isolates, but aflQ showed a good correlation between expression and aflatoxin-production ability.
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Affiliation(s)
- Paula Rodrigues
- IBB - Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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Criseo G, Racco C, Romeo O. High genetic variability in non-aflatoxigenic A. flavus strains by using Quadruplex PCR-based assay. Int J Food Microbiol 2008; 125:341-3. [DOI: 10.1016/j.ijfoodmicro.2008.04.020] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 04/03/2008] [Accepted: 04/24/2008] [Indexed: 10/22/2022]
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Accinelli C, Abbas H, Zablotowicz R, Wilkinson J. Aspergillus flavus aflatoxin occurrence and expression of aflatoxin biosynthesis genes in soil. Can J Microbiol 2008; 54:371-9. [DOI: 10.1139/w08-018] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The carcinogen aflatoxin B1 (AFB1) produced by Aspergillus flavus is a major food safety concern in crops. However, information on AFB1 occurrence in soil and crop residue is scarce. A series of experiments investigated the occurrence of AFB1 in soil and corn residues and ascertained the ecology of A. flavus in a Dundee silt loam soil. Samples of untilled soil (0–2 cm) and residues were collected in March 2007 from plots previously planted with a corn isoline containing the Bacillus thuringiensis (Bt) endotoxin gene or the parental non-Bt isoline. AFB1 levels were significantly different in various corn residues. The highest AFB1 levels were observed in cobs containing grain, with 145 and 275 ng·g–1in Bt and non-Bt, respectively (P ≥ F = 0.001). Aflatoxin levels averaged 3.3 and 9.6 ng·g–1in leaves and (or) stalks and cobs without grain, respectively. All soils had AFB1 ranging from 0.6 to 5.5 ng·g–1with similar levels in plots from Bt and non-Bt corn. Based on cultural methods, soil contained from log103.1 to 4.5 A. flavus cfu·g–1with about 60% of isolates producing aflatoxin. Laboratory experiments demonstrated that AFB1 is rapidly degraded in soil at 28 °C (half-life ≤ 5 days). The potential of the soil A. flavus to produce aflatoxins was confirmed by molecular methods. Transcription of 5 aflatoxin biosynthesis genes, including aflD, aflG, aflP, aflR, and aflS, were detected by reverse transcription – polymerase chain reaction analysis in soil. Although AFB1 appears to be transient in soils, it is clear that AFB1 is produced in surface soil in the presence of corn residues, as indicated by A. flavus cfu levels, AFB1 detection, and expression of aflatoxin biosynthetic genes.
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Affiliation(s)
- Cesare Accinelli
- Department of Agro-Environmental Science and Technology, University of Bologna, 40127 Bologna, Italy
- United States Department of Agriculture – Agriculture Research Service (USDA–ARS), Crop Genetics and Production Research Unit, Stoneville, MS 38776, USA
- USDA–ARS Southern Weed Science Research Unit, Stoneville, MS 38776, USA
- Department of Biochemistry and Molecular Biology, Mississippi State University, Starkville, MS 39762, USA
| | - H.K. Abbas
- Department of Agro-Environmental Science and Technology, University of Bologna, 40127 Bologna, Italy
- United States Department of Agriculture – Agriculture Research Service (USDA–ARS), Crop Genetics and Production Research Unit, Stoneville, MS 38776, USA
- USDA–ARS Southern Weed Science Research Unit, Stoneville, MS 38776, USA
- Department of Biochemistry and Molecular Biology, Mississippi State University, Starkville, MS 39762, USA
| | - R.M. Zablotowicz
- Department of Agro-Environmental Science and Technology, University of Bologna, 40127 Bologna, Italy
- United States Department of Agriculture – Agriculture Research Service (USDA–ARS), Crop Genetics and Production Research Unit, Stoneville, MS 38776, USA
- USDA–ARS Southern Weed Science Research Unit, Stoneville, MS 38776, USA
- Department of Biochemistry and Molecular Biology, Mississippi State University, Starkville, MS 39762, USA
| | - J.R. Wilkinson
- Department of Agro-Environmental Science and Technology, University of Bologna, 40127 Bologna, Italy
- United States Department of Agriculture – Agriculture Research Service (USDA–ARS), Crop Genetics and Production Research Unit, Stoneville, MS 38776, USA
- USDA–ARS Southern Weed Science Research Unit, Stoneville, MS 38776, USA
- Department of Biochemistry and Molecular Biology, Mississippi State University, Starkville, MS 39762, USA
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