Biological detoxification of Aflatoxin B1 by Bacillus licheniformis CFR1

Abstract

Aflatoxin B1 is the most harmful among the mycotoxins commonly present in food and feed, and it may lead to hepatocellular carcinoma in humans and animals. Therefore, limiting its exposure to humans and livestock is very much essential. The present study aims to isolate and characterize Aflatoxin B1 detoxifying bacteria from various sources, to develop a safe and environment-friendly strategy for Aflatoxin B1 management. Fifty-six bacteria were isolated using a media amended with coumarin as a sole carbon source. Seven strains showed more than 70% reduction of AFB1 in liquid culture media. Among them, isolate CFR1 reduced Aflatoxin B1 by 94.7%, and it was selected for further studies. CFR1 was identified as Bacillus licheniformis CFR1, by biochemical characterization and 16S rRNA gene sequencing. The cell-free supernatant of B. licheniformis CFR1 was able to degrade AFB1 efficiently than the cell lysate. The degradation of AFB1 was examined using High-Performance Thin Layer Chromatography (HPTLC), High-Performance Liquid Chromatography (HPLC) and Electron spray ionization-Mass Spectrometry (ESI-MS). The optimal temperature, time, and pH of the medium for the maximum degradation of Aflatoxin B1 were found to be 37 °C, 24 h and 7, respectively. Furthermore, Ames test for mutagenicity showed that when treated with B. licheniformis CFR1 extracellular fraction coincided with the loss of Aflatoxin B1 mutagenicity. To the best of our knowledge, this is the first study that shows more than 90% degradation of AFB1 by B. licheniformis. Thus, B. licheniformis CFR1 might be an excellent candidate for bioremediation and detoxification of Aflatoxin B1 from both field and food matrices.