Incidence of fungal contamination in a Romanian bakery: a molecular approach

摘要

Fungal infections are responsible for the quality and safety of bakery products. The present approach aims to screen the incidence of fungi species in a Romanian bakery and to identify the Aspergillus strains that produce aflatoxins. Conventional methods were used to isolate the fungal strains from the air in different bakery areas, and molecular techniques (multiplex PCR reaction, ITS-RFLP method) were employed for the selective detection of A. flavus, A. niger, A. fumigatus, and A. ochraceus. The results obtained by conventional methods revealed that fungal contamination was different from one area to another, the smallest contamination being detected in the fermentation room, 2.5 cfu/m’, and the highest in the partition of dough (14 cfu/m’) and in the slicing and packing (14 cfu/m’) areas. The most frequent genera in all production areas, identified by the colonies morphology and microscopic examination were: Aspergillus, Penicillium, Alternaria, Fusarium, Ulocladium, Neurospora and Trichoderma. The presence of Neurospora genus fungi was also noticed in some specific areas, like the toast and packaging area, the cooling area and package storage room; however, the counting of colonies was not possible. Molecular techniques, performed on isolated Aspergillus strains (the most frequently recorded), revealed that results were highly correlated with classical identification, with the exception of two samples of A. fumigatus and one sample of A.ochraceus, suspected to be contaminated. Although classical methods based on fluorescence appearance on the coconut medium did not show the presence of A. flavus aflatoxin producing strains, the simultaneous presence of both PCR products corresponding to norl and aflpR genes suggests that at least one strain of the isolated A. flavus could produce aflatoxin.