Spent mushroom substrate: Degrading DON mycotoxin
In a recently published study, researchers found the extracts from spent mushroom substrate inhibit the growth of Fusarium graminearum (the fungi that produce deoxynivalenol (DON) mycotoxin). Their findings describe how the extracts degrades DON in feed and in pig and poultry GIT, in a simulation set-up.
BY MATTHEW WEDZERAI, INDEPENDENT CORRESPONDENT D
ON is responsible for one of the most severe pollutions in feeds and ingredients. Among other fungi, DON is produced by the fungi Fusarium graminearum, and the grains most affected by this
fungi are wheat, barley, oats, and corn – posing a threat to animal and human health. Spent mushroom substrate is defined as the spent substrate (growing media) and all mushroom residuals resulting from the harvest of mushroom fruit bodies at the growing facili- ties. Little is known about the degradability of DON by the spent mushroom (Flammulina velutipes) substrate extracts (manganese peroxidase and lignin peroxidase). Flammulina velutipes, also known as velvet shank, is a species of edible mushroom.
Study set-up The effects of two extracts (manganese peroxidase (MnP) and lignin peroxidase (LiP)) from spent mushroom (Flammulina velutipes) substrate were tested on their ability to inhibition the production of DON and growth of DON-producing fungi F. graminearum KR1 in an in vitro setup. The degradability of DON in simulated pig and poultry GIT was also determined only for lignin peroxidase extract as it was found, in a pre- test, that LiP treatment has a better antifungal effect than MnP treatment and no significant difference was observed between MnP and LiP treatments on reduction of DON pro- duction. For the simulation, different DON concentrations for pig (1 mg/kg) and poultry (5 mg/kg) feeds were used. 180 g of pig and poultry feeds, each with DON concentration of 0.5
mg/kg DON, were premixed with LiP powder (50 U/g) before being mixed with the medium that mimicked the stomach and intestinal conditions (pH and time) for pigs and poultry.
Mycotoxin in animal products According to the researchers, the passage of mycotoxins or their metabolites into animal products through the contaminated diet is an issue of great importance for the consumers, and the market. “There is a variation in tissue deposition of the mycotoxins among farm animals that is attributed to differences in their absorption and metabolism. In general, the accumulation of mycotoxins and their metabolites in animal muscle tissues is low, often below detection limits due to their intense metabolism in the liver. However, blood, kidney, and liver contain higher levels of mycotoxins and their metabolites than muscles and adipose tissue. As a result, special attention should be given if these offals are consumed”, they say.
▶ MYCOTOXINS | NOVEMBER 2021
The primary DON toxigenic fungi are Fusari- um culmorum and Fusarium graminearum. Both fungi affect wheat, barley, oats and corn.
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PHOTO: MAXPIXEL’S CONTRIBUTORS
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