Purification and characteristics of an aflatoxin B1 degradation enzyme isolated from Pseudomonas aeruginosa

ABSTRACT

Aflatoxin is a highly toxic mycotoxin produced by Aspergillus flavus and A.parasitic fungus. Since it contaminates food and grain widely, it has seriously endanger the health of human beings and animals. Some microorganisms that exist in nature can degrade aflatoxin. In this paper, the biological AFB_{1 (}aflatoxin B₁₎ -degradation by Pseudomonas aeruginosa M19 was evaluated. We found that the culture supernatant of Pseudomonas aeruginosa M19 added with proteinase K (Prok), SDS and heating significantly decreased degradation capacity. Pseudomonas AFB₁-degrading enzyme (PADE) was purified from Pseudomonas aeruginosa M19 by a three-step procedure including ammonium sulfate fractional precipitation and ion exchange chromatography and gel filtration chromatography. PADE was purified 175-fold with a recovery of 35%, and an ultimate specific activity of 6.1 × 10⁴ U/mg was achieved. The molecular weight of PADE estimated by SDS-PAGE is about 48 kDa. PADE displayed the highest degradation activity for AFB₁ at 65°Cand pH 6.0. Cu²⁺ and Fe³⁺ strongly enhanced the activity, whereas Ca²⁺ and Zn²⁺ strongly inhibited the activity. These findings indicate that PADE from Pseudomonas.aeruginosa M19 is a promising candidate for AFB₁ biodegradation.

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