Construction of Bifunctional Saccharomyces cerevisiae with Ability to Detoxify Mycotoxins
The contamination of mycotoxins is common in feed and becomes one major hurdle preventing healthy breeding of animals.There are many types of mycotoxins,among which aflatoxins,and particularly aflatoxin B1(AFB1)have the highest impact and harm.Therefore,developing new methods for detoxification of mycotoxins in feeds is currently a hot research topic.In this study,Saccharomyces cerevisiae strains were first isolated and four were compared for their absorption rates of AFB1.It was then discovered that,in comparison with other methods including heating and mannanase treatment and strains,glucanase treatment of CEN.PK had the highest absorption of AFB1,which could reach as high as 53.3%±8.2%.Then,CEN.PK was used as the host cell to constitutively express a myo-inositol oxidase gene from Flavobacterium johnsoniae(FjMiox).The engineered yeast could convert 1 g·L-1 of myo-inositol into 0.273 g·L-1 of glucuronic acid.In the liver of animals,the glucuronic acid could be conjugated with mycotoxins by enzymatic catalysis to increase their water solubility,thereby facilitating their excretion.Therefore,the engineered Saccharomyces cerevisiae able to synthesize glucuronic acid combines the functions of binding the mycotoxin in the gut and conjugating to the mycotoxin in the liver,which could provide a new solution to combat the contamination of aflatoxins in feeds.
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