Degradation of aflatoxin B1 from naturally contaminated maize using the edible fungus Pleurotus ostreatus

Lauren W Jackson,Barry M Pryor

doi:10.1186/s13568-017-0415-0

Lauren W Jackson, Barry M Pryor

Open Access

https://doi.org/10.1186/s13568-017-0415-0

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Journal: AMB Express	Publication Date: Jun 2, 2017
Citations: 21	License type: open-access

Affiliation: University of Minnesota, University of Arizona

Abstract

Aflatoxins are highly carcinogenic secondary metabolites that can contaminate approximately 25% of crops and that cause or exacerbate multiple adverse health conditions, especially in Sub-Saharan Africa and South and Southeast Asia. Regulation and decontamination of aflatoxins in high exposure areas is lacking. Biological detoxification methods are promising because they are assumed to be cheaper and more environmentally friendly compared to chemical alternatives. White-rot fungi produce non-specific enzymes that are known to degrade aflatoxin in in situ and ex situ experiments. The aims of this study were to (1) decontaminate aflatoxin B1 (AFB1) in naturally contaminated maize with the edible, white-rot fungus Pleurotus ostreatus (oyster mushroom) using a solid-state fermentation system that followed standard cultivation techniques, and to (2) and to assess the risk of mutagenicity in the resulting breakdown products and mushrooms. Vegetative growth and yield characteristics of P. ostreatus were not inhibited by the presence of AFB1. AFB1 was degraded by up to 94% by the Blue strain. No aflatoxin could be detected in P. ostreatus mushrooms produced from AFB1-contaminated maize. Moreover, the mutagenicity of breakdown products from the maize substrate, and reversion of breakdown products to the parent compound, were minimal. These results suggest that P. ostreatus significantly degrades AFB1 in naturally contaminated maize under standard cultivation techniques to levels that are acceptable for some livestock fodder, and that using P. ostreatus to bioconvert crops into mushrooms can reduce AFB1-related losses.

Highlights

Aflatoxins are highly carcinogenic secondary metabolites produced by several members of Aspergillus section Flavi that contaminate an array of important food crops (Cotty et al 1994)
Growth characteristics of P. ostreatus cultivated on aflatoxin B1 (AFB1)‐contaminated maize The presence of aflatoxin did not appear to inhibit the vegetative growth of any P. ostreatus strains (Table 1)
Mushrooms produced by N001 cultivated on maize with the greatest concentration (2500 ng g−1) of AFB1matured significantly faster than those grown from maize contaminated at 250 ng g−1, but did not differ from those grown on maize contaminated at 0 or 25 ng g−1 (Table 1)

Summary

Introduction

Aflatoxins are highly carcinogenic secondary metabolites produced by several members of Aspergillus section Flavi that contaminate an array of important food crops (Cotty et al 1994). These mycotoxins are responsible for causing adverse health conditions in humans and other animals such as growth retardation, immune suppression, hepatocellular carcinoma, and death (Kensler et al 2011). Aflatoxins are tightly regulated in the U.S and European Union (EU), where the maximum allowable aflatoxin concentration in foods intended for human consumption. Biological decontamination methods present possible advantages to chemical processes because they are less likely to be detrimental to the environment and are assumed to be more cost-effective (Guan et al 2011).

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