Enzymatic degradation of mycotoxins during grain processing
Methods, compositions, and systems for steeping, propagation and fermentation, particularly large-scale operations for production of starch and ethanol and fermentation product streams are provided. Addition of mycotoxin mitigating enzymes or microorganisms expressing mycotoxin mitigating enzymes to steeping, propagation, and/or fermentation tanks, and/or to post-fermentation product streams, mitigates mycotoxin levels in fermentation co-products obtained from mycotoxin contaminated feedstocks.
1. A livestock feed composition comprising distiller's grain sourced from deoxynivalenol (DON)-contaminated feedstock selected from the group consisting of corn, sorghum, or wheat fermented in the presence of a lysate derived from a microorganism expressing deoxynivalenol hydroxylase (Ddna), wherein levels of DON in the livestock feed composition are decreased relative to levels of DON in a livestock feed composition obtained from the same feedstock fermented in the absence of the lysate.
2. The livestock feed composition of claim 1 , wherein the microorganism expresses an enzyme encoded by: a polynucleotide comprising a nucleotide sequence set forth in SEQ ID NO: 1, encoding deoxynivalenol hydroxylase (Ddna), or a polynucleotide comprising a nucleotide sequence having at least about 95% sequence identity to SEQ ID NO: 1.
3. The livestock feed composition of claim 2 , wherein the microorganism further expresses enzymes encoded by a KdR gene and a KdX gene.
4. The livestock feed composition of claim 3 , wherein the KdR gene, KdX gene, and Ddna gene are provided on an expression cassette comprising a polynucleotide comprising a nucleotide sequence set forth in SEQ ID NO: 10, or a polynucleotide comprising a nucleotide sequence having at least about 95% sequence identity to SEQ ID NO: 10.
5. The livestock feed composition of claim 1 , wherein the microorganism is a yeast.
6. The livestock feed composition of claim 5 , wherein the yeast is S. cerevisiae.
7. The livestock feed composition of claim 5 , wherein the yeast is Pichia pastoris.
8. The livestock feed composition of claim 1 , wherein the microorganism is a bacterium.
9. The livestock feed composition of claim 1 , wherein the feedstock is ground corn.
10. The livestock feed composition of claim 1 , wherein the levels of mycotoxin are decreased to less than about 2 ppm.
11. A method of producing the livestock feed of claim 1 , the method comprising: fermenting a DON contaminated feedstock in the presence of a lysate obtained from a microorganism expressing deoxynivalenol hydroxylase.
12. The method of claim 11 , wherein the lysate is obtained from a microorganism expressing an enzyme encoded by a polynucleotide comprising a nucleotide sequence set forth in SEQ ID NO: 1, encoding deoxynivalenol hydroxylase (Ddna), or a polynucleotide comprising a nucleotide sequence having at least about 95% sequence identity to SEQ ID NO: 1.
13. The method of claim 12 , wherein the lysate is obtained from a microorganism further expressing the proteins encoded by a KdR gene or KdX gene.
14. The method of claim 13 , wherein the KdR gene, KdX gene, and Ddna gene are provided on an expression cassette comprising a polynucleotide comprising a nucleotide sequence set forth in SEQ ID NO: 10, or a polynucleotide comprising a nucleotide sequence having at least about 95% sequence identity to SEQ ID NO: 10.
15. The method of claim 11 , wherein the levels of mycotoxin in the livestock feed are less than about 2 ppm.