Mycotoxin inactivating enzymes as feed additives

Presented at the European Summit of Industrial Biotechnology, 14th-16^th November 2022, Graz, Austria by Daniel Incze

 Authors: Incze, Daniel Janos^1,2; Dr. Bata, Zsofia²; Dr. Poppe, Laszlo¹

Fumonisins are one of the most prevalent mycotoxins produced by certain Fusarium species, that contaminate crops globally, predominantly corn. The most important and prominent substance of the family is Fumonisin B₁ (FB₁). FB₁inhibits ceramide synthase, an important enzyme of the sphingolipid biosynthesis in mammals. The altered sphingolipid metabolism can lead to different serious adverse health effects in humans and animals, therefore crops contaminated with high levels of FB1 should be removed from the food or feed chain. Physical or chemical decontamination of crops are often not effective enough, however, enzymatic detoxification can be a solution to the problem. Fumonisin esterases cleave the two tricarballylic acid group of FB₁, leading to partially and fully hydrolysed FB₁ (pHFB₁ and HFB₁, respectively). These metabolites don’t inhibit ceramide synthase, therefore possess significantly lower toxicity. Fumonisin esterases are excellent candidates of food or feed additives against FB₁ contamination, however, kinetics and mechanism of these enzymes are not well characterized yet. The aim of the study is to understand the detailed enzymatic mechanism of two of these biocatalysts, to fine tune already existing product. For that reason, the enzymes were expressed in Pichia pastoris expression system, and kinetic constants were evaluated, with both FB₁ and pHFB₁ as substrate. It was found that fumonisin esterases selectively produce one of the two possible pHFB₁, and the two enzymes significantly differ in the affinity towards pHFB₁. We proposed a reaction mechanism based on our results, although further structure analyses are necessary.

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 ¹ Budapest University of Technology and Economics, Department of Organic Chemistry and Technology, Bioorganic Chemistry Research Group, Budapest

² Dr. Bata Ltd., Research and Development Laboratory, Ócsa