Screening Of A T-2 Toxin Degradation Strain And Studying On Extraction Of The Degradation Enzyme And The Degradation Effect For T-2 Toxin

As a member of Trichothecenes mycrotoxins produced by a variety of Fusarium molds, T-2 toxin is widely distributed in nature, especially in field crops and stored grain. Considering the toxicity of T-2 toxin for animals and human health, it is extremely urgent for us to study on degradation of T-2 toxin. It is showed that some strains in nature will produce mycotoxins in the specific environment. Based on stable properties, T-2 toxin is highly toxic with the functional structure of epoxy ring, hydroxyl, acetoxyl group and is difficult to be damaged by the external environment. Thus, in this study, a strain had been screened to reduce T-2 toxin by the biological degradation method. Moreover, we observed and identified the morphology structure of the strain the properties of the enzyme which was extracted from the strain. Additionally, I also summarized the degradated effect and products of the enzyme. The main contents were as follows:(1) By screening a strain from soil using the phenyl epoxy ethane as the only carbon source, we found that the strain had a capable of degrading T-2 toxin. Thus, I confirmed that the strain was an extracellular enzyme.(2) By morphological observation, strain microscopy, electron microscope scanning and molecular biology identification, I preliminary identified that the strain was a member of Aspergillus. The DNA length of the strain was 621bp by the sequence analysis and the result showed that the homology of strain with several aspergillus nigers was about 99%, which indicated the strain was aspergillus niger.(3) Using SDS-PAGE to analysis the molecular weight of the target enzyme, the result showed that the protein weight was between 49kDa to 85kDa, we preliminary estimated the protein molecular weight was 50kDa. In this study, I found that the optimum temperature and pH of the enzyme were 40 ℃ and 8.5. The enzyme was stable under 40 ℃ with pH ranging from 6 to 8. Meanwhile, the enzyme activity could be enhanced by Ca2+、Mg2+、Fe2+, carbinol, ethanol and EDTA, while inhibited byZn2+、Cu2+、Mn2+,acetone and SDS.(4) The result of HPLC showed that the enzyme can reduce T-2 toxin and the degradation rate was above 70%. In addition, the result by GC indicated T-2 toxin may be degradated by the enzyme and created some new substance.(5) I selected health mice and randomly divided them into 5 groups, mice with a normal diet as the blank control group while T-2 toxin in mice diet as a positive control group, and the treatment groups of mice in the diets adding T-2 toxin with different concentrations of enzyme (1%、.5%、2%), Feeding 30 days, we found that the T-SOD activity of T-2 toxin was significantly lower than the control group while the content of MDA and LDH was significantly higher than the control group. When we added 1.5%,2% enzyme in toxic feed, respectively, T-SOD activity was significantly lower than the positive group. Meanwhile, the content of MDA, LDH was significantly higher than positive group. The conclusion from the biochemical indexes of mice was that the degradation effect of T-2 toxin was same with 1.5% and 2% of the enzyme. Thus, I should add 1.5% enzyme in feed for the purpose of save cost.