Screening and Degradation Characteristics of a Fumonisin B1-Degrading Fungal Strain

Abstract

A fungal strain capable of degrading fumonisin B1 (FB1) from ground maize samples heavily contaminated with fumonisin was obtained by enrichment culture method. The strain was named as FDS-2, and was characterized for its growth and degradation characteristics, and the initial degradation pathway of FB1 by FDS-2 was investigated. The strain was identified as Exophiala spinifera according to its culture characteristics, microscopic characteristics and phylogenetic tree based on RNA-internal transcribed spacer (ITS) sequence characteristics. The optimum growth and degradation conditions were 30 ℃ and pH 5.0. Under these conditions, the strain could completely degrade 250 μg of FB1 within 48 h. Intracellular FB1-degrading enzymes were discovered in this strain. Using liquid chromatography-mass spectrometry (LC-MS) to analyze the degradation products, it was determined that the primary degradation pathway began with the degradation of FB1 into hydrolyzed FB1. This study provides a strain resource and a theoretical basis for the biodegradation of fumonisin in grain and feed.

Keywords

• fumonisin b1; biodegradation; exophiala spinifera; degradation pathway