Isolation and identification of an extracellular enzyme from Aspergillus Niger with Deoxynivalenol biotransformation capability

Abstract

In this study, the purification and characterization of an extracellular enzyme form Aspergillus niger was performed. With an optimized protocol, it was conducted a 42.6-fold purification with a yield of 26.2%. The purified lipase had a monomeric molecular weight of 40.5kDa and an isoelectric point of 6.01, and its maximum enzyme activity could be achieved at 40°C and pH 7.5-9.0. The enzyme could be activated by Ca2+, Mg2+ and Fe2+, while its activity could be inhibited by Zn2+ and Cu2+. Additionally, organic compounds exerted an inhibitory effect on the enzyme activity in a descending order of methanol, ethanol, DMSO, EDTA, acetone. Meanwhile, the specificity analysis of the enzyme indicated a preference to tributyrin and vegetable oils as well as long-chain fatty acid methyl esters (C12-C18). Most importantly, this enzyme could successfully transform deoxynivalenol (DON). Using HPLC analysis，it was detected a biotransformation rate of more than 70%.The liquid chromatography-mass spectrometry (LC-MS) analysis showed that the molecular weight of the transformation product was 18.0 larger than that of DON, indicating that DON could be hydrolyzed by the enzyme. Overall, the proposed method here provides a new avenue for reducing the toxicity of DON, which appears to have a wide application outlook for DON biotransformation.