AUTHOR=Yue Xiaofeng , Ren Xianfeng , Fu Jiayun , Wei Na , Altomare Claudio , Haidukowski Miriam , Logrieco Antonio F. , Zhang Qi , Li Peiwu 

TITLE=Characterization and mechanism of aflatoxin degradation by a novel strain of Trichoderma reesei CGMCC3.5218

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1003039

DOI=10.3389/fmicb.2022.1003039

ISSN=1664-302X

ABSTRACT=<p>Aflatoxins, which are produced mainly by <italic>Aspergillus flavus</italic> and <italic>A. parasiticus</italic>, are recognized as the most toxic mycotoxins, which are strongly carcinogenic and pose a serious threat to human and animal health. Therefore, strategies to degrade or eliminate aflatoxins in agro-products are urgently needed. We investigated 65 <italic>Trichoderma</italic> isolates belonging to 23 species for their aflatoxin B<sub>1</sub> (AFB<sub>1</sub>)-degrading capabilities. <italic>Trichoderma reesei</italic> CGMCC3.5218 had the best performance, and degraded 100% of 50 ng/kg AFB<sub>1</sub> within 3 days and 87.6% of 10 μg/kg AFB<sub>1</sub> within 5 days in a liquid-medium system. CGMCC3.5218 degraded more than 85.0% of total aflatoxins (aflatoxin B<sub>1</sub>, B<sub>2</sub>, G<sub>1</sub>, and G<sub>2</sub>) at 108.2–2323.5 ng/kg in artificially and naturally contaminated peanut, maize, and feed within 7 days. Box–Behnken design and response surface methodology showed that the optimal degradation conditions for CGMCC3.5218 were pH 6.7 and 31.3°C for 5.1 days in liquid medium. Possible functional detoxification components were analyzed, indicating that the culture supernatant of CGMCC3.5218 could efficiently degrade AFB<sub>1</sub> (500 ng/kg) with a ratio of 91.8%, compared with 19.5 and 8.9% by intracellular components and mycelial adsorption, respectively. The aflatoxin-degrading activity of the fermentation supernatant was sensitive to proteinase K and proteinase K plus sodium dodecyl sulfonate, but was stable at high temperatures, suggesting that thermostable enzymes or proteins in the fermentation supernatant played a major role in AFB<sub>1</sub> degradation. Furthermore, toxicological experiments by a micronucleus assay in mouse bone marrow erythrocytes and by intraperitoneal injection and skin irritation tests in mice proved that the degradation products by CGMCC3.5218 were nontoxic. To the best of our knowledge, this is the first comprehensive study on <italic>Trichoderma</italic> aflatoxin detoxification, and the candidate strain <italic>T. reesei</italic> CGMCC3.5218 has high efficient and environment-friendly characteristics, and qualifies as a potential biological detoxifier for application in aflatoxin removal from contaminated feeds.</p>