Detoxification of Aflatoxin B1 by Cell-free Extract of Aspergillus oryzae MAO 103

Introduction: Aflatoxins are a group of mycotoxins which are produced mainly by toxigenic Aspergillus flavus and A. parasiticus and classified as a human carcinogen. Biological AFB₁-detoxification is the most desirable approach to reduce AFB₁ in food.

Purpose: The aim of this study was to investigate the AFB₁-detoxification activity of cell-free extracts of Aspergillus oryzae MAO 103.

Methods: The AFB₁-biodegradation activities were investigated using cell-free extracts of A. oryzae MAO 103 (NCBI accession ID: KY020433). The AFB₁-detoxification activities of the extract were assayed in different pH (pH3~10), temperature (25~40℃), and cell cultivation time (4~16 days), and the amount of AFB₁ was analyzed by HPLC-FLD.

Results: The cell-free extract of A. oryzae MAO 103 showed significant AFB₁-detoxification activities; AFB₁ was reduced by more than 97% within 1 day (initial concentration: 0.05 - 1 μg/mL of AFB₁) and about 90% of AFB₁ was decreased in 10 minute. The highest AFB₁-reduction was achieved in the 8-day cell-free extract containing 475.8 μg/mL of total protein. The reaction was enhanced by NADPH (4 mmol) and NaIO₄ (1~3 mmol).

Significance: The cell-free extract of A. oryzae MAO 103 showed significant biodegradation activity on AFB₁, indicating that the results could be applied to food and feed industries. The AFB₁-biodegradation activity by the cell-free extract of A. oryzae MAO 103 suggests the involvement of cytochrome P-450 monooxygenase in the detoxification reaction.