Identification and Characterization of a Novel Strain of Bacillus safensis M7L4 Capable of Degrading Zearalenone and Analysis of Related Key Enzymes

Abstract

A bacterial strain with high efficiency of zearalenone (ZEN) removal was isolated from wheat samples by enrichment culture method using ZEN as a major carbon source. By morphological observation, 16S rDNA sequence and gyrase B (gyrB) sequence analysis, the strain was identified and named as Bacillus safensis M7L4. ZEN at a concentration of 10 μg/mL could be completely degraded by viable cells of strain M7L4 in 24 hours when cultured in minimal salt medium. By ultra-high performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS), the transformation product of ZEN was identified as zearalenone-phosphate (ZEN-P) with a mass-to-charge ratio (m/z) of 397.1. The phosphoenolpyruvate (PEP)-utilizing enzyme gene of Bacillus safensis (named BsaPUE) was amplified from M7L4 and inserted into the pET-28(+) vector. The recombinant Escherichia coli BL21(DE3) harboring the plasmid pET-28a(+)-BsaPUE was induced with isopropyl-beta-D-thiogalactopyranoside (ITPG) and the expressed protein was purified by Ni-NTA chromatography. The recombinant BsaPUE exhibited phosphotransferase activity, which could entirely transform ZEN (10 μg/mL) to ZEN-P in the presence of ATP and Mg2+ within 30 minutes. Strain M7L4 and its phosphotransferase are promising resources for the biodetoxification of ZEN.

Keywords

• zearalenone; bacillus; degradation; zearalenone-phosphate