Abstract

Fumonisin contamination of maize is considered a serious problem in most maize-growing regions of the world,due to the widespread occurrence of these mycotoxins and their association with toxicosis in livestock andhumans. Fumonisins are produced primarily by species of Fusarium that are common in maize grain, but alsoby some species of Aspergillus sect. Nigri, which can also occur on maize kernels as opportunistic pathogens. Understandingthe origin of fumonisin contamination in maize is a key component in developing effectivemanagementstrategies. Although some fungi in Aspergillus sect. Nigri are known to produce fumonisins, little is knownabout the species which are common in maize and whether they make a measurable contribution to fumonisincontamination ofmaize grain. In thiswork,we evaluated populations of Aspergillus sect. Nigri isolated frommaizein USA and Italy, focusing on analysis of housekeeping genes, the fum8 gene and in vitro capability of producingfumonisins. DNA sequencing was used to identify Aspergillus strains belonging to sect. Nigri, in order to comparespecies composition between the two populations, which might influence specificmycotoxicological risks. Combinedbeta-tubulin/calmodulin sequences were used to genetically characterize 300 strains (199 from Italy and101 fromUSA)which grouped into 4 clades: Aspergilluswelwitschiae (syn. Aspergillus awamori, 14.7%), Aspergillustubingensis (37.0%) and Aspergillus niger group 1 (6.7%) and group 2 (41.3%). Only one strain was identified as Aspergilluscarbonarius. Species composition differed between the two populations; A. niger predominated amongthe USA isolates (69%), but comprised a smaller percentage (38%) of Italian isolates. Conversely, A. tubingensisand A. welwitschiae occurred at higher frequencies in the Italian population (42% and 20%, respectively) than inthe USA population (27% and 5%). The evaluation of FB2 production on CY20S agar revealed 118 FB2 producingand 84 non-producing strains distributed among the clades: A. welwitschiae, A. niger group 1 and A. niger group2, confirming the potential of Aspergillus sect. Nigri species to contribute to total fumonisin contamination ofmaize. A higher percentage of A. niger isolates (72.0%) produced FB2 compared to A. welwitschiae (36.6%). Thepercentage of FB2-producing A. niger strains was similar in the USA and Italian populations; however, the predominanceof A. niger in the USA population suggests a higher potential for fumonisin production. Some strainswith fum8 present in the genome did not produce FB2 in vitro, confirming the ineffectiveness of fum8 presence asa predictor of FB2 production.

Autore Pugliese

• Susca Antonia , Moretti Antonio , Logrieco Antonio Francesco , Haidukowski Edith Miriam , Stea Gaetano

Tutti gli autori

• Susca A.; Moretti A.; Stea G.; Villani A.; Haidukowski M.; Logrieco A.; Munkvold G.

Titolo volume/Rivista

International journal of food microbiology

Anno di pubblicazione

2014

ISSN

0168-1605

ISBN

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Numero di citazioni Wos

Nessuna citazione

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Numero di citazioni Scopus

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Settori ERC

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Codici ASJC

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