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

Xiaofeng Yue; Xianfeng Ren; Jiayun Fu; Na Wei; Claudio Altomare; Miriam Haidukowski; Antonio F Logrieco; Qi Zhang; Peiwu Li

doi:10.3389/fmicb.2022.1003039

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

Front Microbiol. 2022 Oct 13:13:1003039. doi: 10.3389/fmicb.2022.1003039. eCollection 2022.

Authors

Xiaofeng Yue^{1

2}, Xianfeng Ren³, Jiayun Fu^{1

2}, Na Wei⁴, Claudio Altomare⁵, Miriam Haidukowski⁵, Antonio F Logrieco⁵, Qi Zhang^{1

2

6}, Peiwu Li^{1

2}

Affiliations

¹ Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China.
² Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China.
³ Institute of Quality Standard and Testing Technology for Agro-products, Shandong Academy of Agricultural Sciences, Jinan, China.
⁴ Institutions of Agricultural Product Quality Standard and Testing Research, Tibet Academy of Agricultural and Animal Husbandry Sciences, Lhasa, China.
⁵ Institute of Sciences of Food Production, National Research Council, Bari, Italy.
⁶ Hubei Hongshan Lab, Wuhan, China.

Abstract

Aflatoxins, which are produced mainly by Aspergillus flavus and A. parasiticus, 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 Trichoderma isolates belonging to 23 species for their aflatoxin B₁ (AFB₁)-degrading capabilities. Trichoderma reesei CGMCC3.5218 had the best performance, and degraded 100% of 50 ng/kg AFB₁ within 3 days and 87.6% of 10 μg/kg AFB₁ within 5 days in a liquid-medium system. CGMCC3.5218 degraded more than 85.0% of total aflatoxins (aflatoxin B₁, B₂, G₁, and G₂) 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 AFB₁ (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 AFB₁ 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 Trichoderma aflatoxin detoxification, and the candidate strain T. reesei CGMCC3.5218 has high efficient and environment-friendly characteristics, and qualifies as a potential biological detoxifier for application in aflatoxin removal from contaminated feeds.

Keywords: Aspergillus flavus; Trichoderma reesei CGMCC3.5218; aflatoxin B1; aflatoxins; degradation; detoxification.