Detoxification of aflatoxin B1 by a Bacillus subtilis spore coat protein through formation of the main metabolites AFQ1 and epi-AFQ1.

Autor: Subagia R; Department of Agrobiotechnology (IFA-Tulln), Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria., Schweiger W; dsm-firmenich, Animal Nutrition and Health R&D Center Tulln, Tulln, Austria., Kunz-Vekiru E; dsm-firmenich, Animal Nutrition and Health R&D Center Tulln, Tulln, Austria., Wolfsberger D; dsm-firmenich, Animal Nutrition and Health R&D Center Tulln, Tulln, Austria., Schatzmayr G; Department of Agrobiotechnology (IFA-Tulln), Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria., Ribitsch D; Department of Agrobiotechnology (IFA-Tulln), Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria., Guebitz GM; Department of Agrobiotechnology (IFA-Tulln), Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria.
Jazyk: angličtina
Zdroj: Frontiers in microbiology [Front Microbiol] 2024 Oct 04; Vol. 15, pp. 1406707. Date of Electronic Publication: 2024 Oct 04 (Print Publication: 2024).
DOI: 10.3389/fmicb.2024.1406707
Abstrakt: A variety of important agricultural crops host fungi from the Aspergillus genus can produce cancerogenic secondary metabolites such as aflatoxins. Consequently, novel strategies for detoxification and their removal from food and feed chains are required. Here, detoxification of Aflatoxin B1 (AFB1) by the Bacillus subtilis multi-copper oxidase CotA (BsCotA) was investigated. This laccase was recombinantly produced in E. coli while codon optimization led to duplication of the amount of active protein obtained. CuCl 2 was added to the cultivation medium leading to a 25-fold increase of V max corresponding to improved incorporation of Cu 2+ into the enzyme protein which is essential for the catalytic reaction. To avoid potential cytotoxicity of Cu 2+ , cultivation was performed at microaerobic conditions indeed leading to 100x more functional protein when compared to standard aerobic conditions. This was indicated by an increase of V max from 0.30 ± 0.02 to 33.56 ± 2.02 U/mg. Degradation kinetics of AFB1 using HPLC with fluorescence detection (HPLC-FLD) analysis indicated a theoretical substrate saturation above solubility in water. At a relatively high concentration of 500 μg/L, AFB1 was decomposed at 10.75 μg/Lh (0.17 nmol * min -1* mg -1 ) at a dosage of 0.2 μM BsCotA. AFQ1 and epi-AFQ1 were identified as the initial oxidation products according to mass spectrometry (i.e., HPLC-MS, HPLC-QTOF). None of these molecules were substrates for laccase but both decomposed in buffer. However, decomposition does not seem to be due to hydration of the vinyl ether in the terminal furan ring. Genotoxicity of the formed AFB1 was assessed in several dilutions based on the de-repression of the bacterial SOS response to DNA damage indicating about 80-times reduction in toxicity when compared to AFQ1. The results of this study indicate that BsCotA has high potential for the biological detoxification of aflatoxin B1.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.
(Copyright © 2024 Subagia, Schweiger, Kunz-Vekiru, Wolfsberger, Schatzmayr, Ribitsch and Guebitz.)
Databáze: MEDLINE
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