Screening Of Don Degrading Bacteria And Study On Its Degradation Characteristics

Deoxynivalenol?DON?,also known as vomitoxin,is a mycotoxin mainly produced by Fusarium,which is widely found in contaminated grains,cereal products and feed,it seriously affects the food safety of cereals and their products.Excessive intake of vomitoxin can seriously threaten the health of human beings or animals.Therefore,the detoxification research of vomitoxin has become a hot research topic.In this study,We use biological methods to degrade vomitoxin,and the concentration of deoxynivalenol was determined by high performance liquid chromatography.By inoculating the toxigenic Fusarium graminearum in corn,the deoxynivalenol was extracted from corn and used as the sole carbon source to isolate and screen multiple degrading bacteria from the soil.The strains with degradation effect more than 30%were selected and rescreened with standard substance as substrate.Two strains were obtained,the degradation rates of strain FMM-1 and strain FMM-hx were 68.40%and 84.62%,respectively.The strain FMM-1 and the strain FMM-hx were subjected to morphological detection,and the whole genome DNA of the strain FMM-1 and the strain FMM-hx was extracted,the 16S rDNA was amplified by PCR and subjected to sequencing analysis.The sequencing result was compared with the Genbank database,the alignment showed that the homology of strain FMM-1 with Pseudomonas aeruginosa was as high as 99%,indicating that the strain FMM-1 is Pseudomonas aeruginosa.The homology of the strain FMM-hx with Bacillus licheniformis was as high as 99%,indicating that the strain FMM-hx is Bacillus licheniformis.The deoxynivalenol degradation effect was detected by the supernatant,the bacterial cells,the cell disrupted liquid of Pseudomonas aeruginosa FMM-1.The degradation rate of supernatant was 54.02%,cell degradation rate was 6.64%,cell breakage liquid degradation rate was2.45%,and the degradation rate of supernatant after heat treatment decreased by 13.00%.The results showed that the main active component of the degradation of Pseudomonas aeruginosa FMM-1 was supernatant.The effects of temperature,pH and metal ions on the degradation activity of supernatant were further studied,the results showed that the optimum temperature for degradation reaction was 45?,the optimum pH value of degradation reaction was 7.0;Cu²⁺and Mn²⁺can promote the degradation activity,and the degradation rate increased by 16.86%and 9.73%,respectively;while Zn²⁺,Fe²⁺and Ca²⁺inhibited the degradation activity,and the degradation rate decreased by 11.52%,27.15%and 38.38%,respectively.Degradation experiments were carried out on the supernatant of Bacillus licheniformis FMM-hx,bacterial cells,cell disrupted solution and heat-treated supernatant,the results showed that the degradation rate of supernatant was 76.83%,cell degradation rate was15.45%,and cell breakage fluid degradation rate was 19.09%.The results indicated that the degradation of deoxynivalenol by Bacillus licheniformis FMM-hx is the result of the combined action of cells,supernatant and cell disrupting solution,but the supernatant which is mainly degrading.We further study the effects of temperature,pH and metal ions on the degradation activity of the supernatant,the results showed that the optimum temperature for degradation reaction was 40?,the optimum pH value of degradation reaction was 6.5,metal ion Mn²⁺has a significant promoting effect on degradation activity,and the degradation effect is improved by 15.32%.The effect of Mg²⁺and Zn²⁺on degradation activity is not obvious,and the degradation activity is only increased by 4.80%and 5.93%,respectively.However,Cu²⁺,Fe²⁺and Ca²⁺inhibited the degradation activity,and the degradation rate decreased by19.50%,23.38%and 9.45%,respectively.The inhibitory effect of Cu²⁺and Fe²⁺was the most significant.We use ultrasonic waves to extract deoxynivalenol from moldy corn,the results showed that the toxin content in corn was reduced by 95%after ultrasonic extraction.The extract is treated with Pseudomonas aeruginosa FMM-1,the results showed that compared with the control group,the degradation rate of vomitoxin in the extract treated with Pseudomonas aeruginosa FMM-1 was 50.00%.After treatment with Bacillus licheniformis FMM-hx,the degradation rate of vomitoxin in the extract was 70.98%.The results showed that two strains of degrading bacteria we screened were able to degrade the vomiting toxins in corn.The degradation effect of Bacillus licheniformis FMM-hx degrading enzyme was studied and its preliminary separation and purification were carried out.However,the isolated protein bands are not single,and it is difficult to determine the target bands.Therefore,further separation and purification are required.By screening the degrading bacteria of deoxynivalenol and studying the relevant factors affecting the degrading activity of the degrading bacteria.It laid the foundation for further research on biodegradation of deoxynivalenol by Pseudomonas aeruginosa FMM-1 and Bacillus licheniformis FMM-hx.