Bio-detoxification of aflatoxin B1 in artificially contaminated maize grains using lactic acid bacteria

Abstract

Aflatoxins are a group of carcinogenic mycotoxins produced by Aspergillus flavus, A. parasiticus, and A. nomius. Due to the ubiquitous occurrence of aflatoxins, preventive and remediative measures are necessary including detoxification techniques. Physical and chemical decontamination strategies are inconvenient. In this study a biological detoxification strategy was tested using bacteria of the Lactobacillus species collected from the biotechnology laboratory at University of Ibadan, Nigeria. Maize grains with moisture content of 17% were artificially inoculated with toxigenic A. flavus (LA 32G_28) and atoxigenic A. flavus (LA32_79) at ambient temperature and four samples of bulk maize grains were prepared at aflatoxin B1 concentrations of 50, 100, 200, and 500 ng/g. To evaluate the detoxifying potential of lactic acid bacteria five different cultures consisting of Lactobacillus acidophilus, L. brevis, L. casei, L. delbruekii, and L. plantarum were used to inoculate the aflatoxin B1–contaminated maize samples at 37°C. After 5 days, the residual aflatoxin B1 on maize was determined. All treatments showed significant reductions (P< 0.05) in aflatoxin B1. Lactic acid bacteria decreased the pH of the medium from 5.0 to 4.0. Pronounced aflatoxin B1 reduction was observed in maize contaminated at 50 ng/g (44.5%), while maize contaminated at 500ng/g was the least reduced (29.9%). L. plantarum was the most efficient organism in degrading aflatoxin B1. Use of lactic acid bacteria, which already has Generally Regarded As Safe (GRAS) status, should be encouraged for use as a bio-detoxification agent for aflatoxins.