The excavation of novel toxin-resistance proteins against trichothecenes toxins in Paramyrothecium roridum

Fhb7-GST catalyzed glutathionylation effectively detoxifies the trichothecene family

Trichothecene (TCN) contamination in food and feed is a serious challenge due to the negative health and economic impacts. Here, we confirmed that the glutathione S-transferase (GST) Fhb7-GST could broadly catalyze type A, type B and type D TCNs into glutathione epoxide adducts (TCN-13-GSHs). To evaluate the toxicity of TCN-13-GSH adducts, we performed cell proliferation assays in vitro, which demonstrated decreased cytotoxicity of the adducts. Moreover, in vivo assays (repeated-dose treatment in mice) confirmed that TCN-13-GSH adducts were dramatically less toxic than the corresponding TCNs. To establish whether TCN-13-GSH was metabolized back to free toxin during digestion, single-dose metabolic tests were performed in rats; DON-13-GSH was not hydrolyzed in vivo, but rather was quickly metabolized to another low-toxicity compound, DON-13-N-acetylcysteine. These results demonstrate the promise of Fhb7-GST as a candidate of detoxification enzyme potentially applied in TCN-contaminated agricultural samples, minimizing the detrimental effects of the mycotoxin.

Mycotoxin risks are lower in biotech corn

Mycotoxins are food contaminants that occur when toxigenic fungi colonize crops. Unfortunately, corn, a major staple crop worldwide, is highly susceptible to mycotoxin contamination. Some mycotoxins, most notably aflatoxin, cause human cancer and other harmful effects such as immunotoxicity and growth impairment. Hence, many nations have set food-safety standards on mycotoxins. Aside from regulations, good agricultural and manufacturing practices lower mycotoxin risks. Agricultural biotechnology has made notable advances in reducing mycotoxins recently. While transgenic Bt corn has been known for years to reduce the mycotoxin fumonisin, new studies have shown its benefit in reducing aflatoxin as well. Other transgenic and RNA-interference corn hybrids target mycotoxin reduction specifically, and gene editing through clustered regularly interspaced short palindromic repeat systems has focused on preventing mycotoxin biosynthesis.