Abstract

Aflatoxin B1 (AFB1) is the most harmful mycotoxin produced mainly by filamentous fungi Aspergillus flavus and A. parasiticus, which can occur as natural contaminants of many agricultural commodities, including maize. Several approaches have been experimented for the removal of aflatoxin from contaminated food and feed, including microbial degradation which, however, has not been so far implemented into practical technologies due to concerns on the quality and safety of the decontaminated materials. The aim of this study was to investigate the capability of the edible and cultivated mushroom Pleurotus eryngii (king oyster mushroom) to degrade AFB1. To this purpouse, nine isolates of P. eryngii were grown on one liquid and one agar medium supplemented with 500 ng/ml of AFB1. After 30 days of growth at 30 ? 1 °C both culture media were processed and analyzed for AFB1 by ultra performance liquid chromatography (UPLC/FLD). In the liquid medium (malt extract broth) all the isolates completely detoxified AFB1. In the solid medium (malt extract-agar supplemented with corn flour and wheat, MEASM) the detoxification ranged from 65 to 84%. In the perspective of developing a technology for bioconversion of aflatoxin-contaminated cereals into added-value feeds, we carried out a pilot study at a laboratory-scale on degradation of AFB1 incorporated in a mushroom cultivation substrate similar to that used in mushroom farms. One strain of P. eryngii (ITEM 13681) was able to bioconvert up to 86% of the AFB1 initially contained in the substrate in 28 days. This value did not change significantly until the maturation of fruit bodies, 42 day post inoculation. The presence of 25% aflatoxin-contaminated maize in the mushroom substrate did not result in a significant reduction of either biological efficiency or yield of the mushroom cultivation. Finally, the analysis of mature fruit bodies did not reveal the presence of detectable amounts of AFB1 or its metabolite aflatoxicol, thus ruling out translocation or "carry-over" of AFB1 through the fungal thallus. These findings make a contribution towards the development of a novel technology for remediation of AFB1-contaminated corn through the exploitation of the degradative capability of P. eryngii.

Autore Pugliese

• Logrieco Antonio Francesco , Altomare Claudio , Haidukowski Edith Miriam

Tutti gli autori

• Branà M. T.; Cimmarusti M. T.; Haidukowski M.; Logrieco A. F.; Altomare C.

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Anno di pubblicazione

2017

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Settori ERC

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