Evaluation of reduced toxicity of zearalenone as measured by the Hep G2 cell assay on degradation enzymes

Abstract

Zearalenone (ZEN), an estrogenic mycotoxin produced by several Fusarium species, is converted to far less toxicity products by enzymes in the culture filtrate of Aspergillus niger FS10. In this study, culture of A. niger that was fermented for 7 days showed the highest protein content and protease activity of 1732.12 μg/mL and 0.53 U/mL, respectively. The culture filtrate separated by a self-assembly Filter Cycle Devices showed that fractions collected at 150 kDa−30 kDa had a significant greater ability to reduce ZEN (89.92%) compared to other fractions (P < 0.01). Furthermore, the active fractions of culture filtrate (AFCF) were analyzed by SDS–PAGE and MALDI-TOF/TOF/MS, and three proteins were found that matched the database for A. niger species with great homology. In order to evaluate the safety of ZEN and the AFCF-treated ZEN, HepG2 cell's survival rate, ROS level, [Ca2+]i production and apoptosis were studied. The cell toxicity of AFCF-treated ZEN is relatively lower than that of ZEN (P < 0.01). Meanwhile, both the ZEN and the AFCF-treated ZEN were negative in Ames test compared to control group (P < 0.05). Therefore, as a safe, effective and economic method, the enzymes could be used as enzyme agents applying in food/feed sector to prevent ZEN contamination.