Aerobic De-Epoxydation of Trichothecene Mycotoxins by a Soil Bacterial Consortium Isolated Using In Situ Soil Enrichment

• Main Authors: Wei-Jie He, Qing-Song Yuan, You-Bing Zhang, Mao-Wei Guo, An-Dong Gong, Jing-Bo Zhang, Ai-Bo Wu, Tao Huang, Bo Qu, He-Ping Li, Yu-Cai Liao
• Format: Article
• Language: English
• Published: MDPI AG 2016-09-01
• Series: Toxins
• Subjects: trichothecenes; deoxynivalenol; aerobic de-epoxydation; soil bacterium; 16S rDNA sequencing
• Online Access: http://www.mdpi.com/2072-6651/8/10/277

Globally, the trichothecene mycotoxins deoxynivalenol (DON) and nivalenol (NIV) are among the most widely distributed mycotoxins that contaminate small grain cereals. In this study, a bacterial consortium, PGC-3, with de-epoxydation activity was isolated from soil by an in situ soil enrichment method. Screening of 14 soil samples that were sprayed with DON revealed that 4 samples were able to biotransform DON into de-epoxydized DON (dE-DON). Among these, the PGC-3 consortium showed the highest and most stable activity to biotransform DON into dE-DON and NIV into dE-NIV. PGC-3 exhibited de-epoxydation activity at a wide range of pH (5–10) and temperatures (20–37 °C) values under aerobic conditions. Sequential subculturing with a continued exposure to DON substantially reduced the microbial population diversity of this consortium. Analyses of the 16S rDNA sequences indicated that PGC-3 comprised 10 bacterial genera. Among these, one species, Desulfitobacterium, showed a steady increase in relative abundance, from 0.03% to 1.55% (a 52-fold increase), as higher concentrations of DON were used in the subculture media, from 0 to 500 μg/mL. This study establishes the foundation to further develop bioactive agents that can detoxify trichothecene mycotoxins in cereals and enables for the characterization of detoxifying genes and their regulation.