Screening And Identification Of Zearalenone-degrading Strain And Optimization Of Zen-degrading Conditions

Zearalenone(ZEN) is one of the secondary metabolites produced by Fusarium sp. which is ubiquitous in nature,resulting in the loss of economic value and nutrition of crops and damaging human and animal's health. Using high throughput trace enrichment technique, a strain was isolated from 83 samples from Hebei, Sichuan and Henan Province including 55 soil samples, 21maize samples and 7 wheat samples; with the analysis of colony morphology, 16S rRNA gene sequence and BIOLOG identification to identify the strain; studying the effects of different conditions on ZEN-degrading. The particular information of this study was described as follows:(1) A ZEN-degrading bacterium strain, named 21-2, was successly isolated from the mycotoxin-contaminated soil from Hebei Province by high throughput trace enrichment microculture technique from 83 samples of Heibei,Sichuan and Henan Province;(2) This strain named 21-2 can highly degrade ZEN. The degradation ratio of ZEN reached 100 % under 37.0℃, 150 rpm after 72.0 h;(3) With the analysis of colony morphology, 16S rRNA gene sequence and BIOLOG identification, the strain 21-2 was preliminary identified as Bacillus licheniformis.. It's one of .the probiotics permitted to be added in animal feeds as live biogen preparation directly,by Ministry of Agriculture of China;(4) To study the effects of different conditions on ZEN-degrading, several factors such as culture medium, incubation time, temperature, initial pH and inoculation size were investigated, the optimum results were : 37.0℃, pH 7.5, 10.0 % inoculation size for 72 h in mineral medium;(5) The ability of cell-free supernatant and cell pellet to degrade ZEN was also investigated, the cell pellet had a strong ability to degrade ZEN while the cell-free supernatant could rarely degrade ZEN, indicating that intracellular enzyme of strain 21-2 may degrade it.