Zearalenone and Its Derivatives α-Zearalenol and ß-Zearalenol Decontamination by Saccharomyces cerevisiae Strains Isolated from Bovine Forage.

Zearalenone (ZEA) and its derivatives are mycotoxins with estrogenic effects on mammals. The biotransformation for ZEA in animals involves the formation of two major metabolites, α- and ß-zearalenol (α-ZOL and ß-ZOL), which are subsequently conjugated with glucuronic acid. The capability of Saccharomyces cerevisiae strains isolated from silage to eliminate ZEA and its derivatives α-ZOL and ß-ZOL was investigated as, also, the mechanisms involved. Strains were grown on Yeast Extract-Peptone-Dextrose medium supplemented with the mycotoxins and their elimination from medium was quantified over time by HPLC-FL. A significant effect on the concentration of ZEA was observed, as all the tested strains were able to eliminate more than 90% of the mycotoxin from the culture medium in two days. The observed elimination was mainly due to ZEA biotransformation into ß-ZOL (53%) and α-ZOL (8%) rather than to its adsorption to yeast cells walls. Further, the biotransformation of α-ZOL was not observed but a small amount of ß-ZOL (6%) disappeared from culture medium. ZEA biotransformation by yeasts may not be regarded as a full detoxification process because both main end-products are still estrogenic. Nonetheless, it was observed that the biotransformation favors the formation of ß-ZOL which is less estrogenic than ZEA and α-ZOL. This metabolic effect is only possible if active strains are used as feed additives and may play a role in the detoxification performance of products with viable S. cerevisiae cells.

Potential of aqueous ozone to control aflatoxigenic fungi in Brazil nuts.

This study aimed to verify the use of aqueous ozone as alternative technology for fungal control. Brazil nuts sterilized were inoculated with either 1 × 10(6) or 1 × 10(7) conidia mL(-1) of Aspergillus flavus (MUM 9201) to determine optimal treatment parameters and different aqueous ozone contact times. These assays showed that the effect of ozone is almost immediate against A. flavus, and the optimum ozone concentration depended on the number of initial viable spores on the shell. The remaining viable spores in the ozone solution were recorded, and the rate of inactivation for each treatment was determined by assessing the ratio between the cfu of each treatment and the control. The ozonized nuts were also cultured to recover the fungal population. Aqueous ozone was effective in reducing the conidia of A. flavus and the natural fungal population associated with Brazil nuts. Aqueous ozone presented a great potential to reduce microorganisms counts in Brazil nuts with a great potential use in packing houses for decontamination step.

Tracing fungi secondary metabolites in Brazil nuts using LC-MS/MS.

This screening aimed to evaluate quantitatively the occurrence of fungal metabolites in Brazil nuts. Nuts were collected from Agroforest production areas in Amazon basin region. A total of 235 mycotoxins (including the most prominent ones) was screened by a multi-mycotoxin method based on HPLC-MS/MS. The recovery of metabolites by the method was between 56 and 136%. Fifteen mycotoxins were detected and quantified, in at least one sample; namely, aflatoxins (AFB(1), AFB(2), AFG(1), and AFM(1)), sterigmatocystin, methyl-sterigmatocystin, kojic acid, citrinin, cyclosporin A, cyclosporin C, cyclosporin D, cyclosporin H, rugulosin, alternariol-methylether and emodin. This is the first study dealing with the detection of the latter nine metabolites in Brazil nuts. Alternariol-methylether (from 0.75 to 3.2 µg/kg) was the only metabolite detected in all analyzed samples.