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Biosynthesis of zearalenone conjugates by fungi

  • Zearalenone (ZEN) and its sulfate and glucoside conjugates have been detected in (a broad variety of) food and feed commodities1. Both conjugated derivatives are formed as part of fungal or plant secondary metabolism and thus, belong to the group of modified mycotoxins2. After consumption of contaminated foodstuff, the conjugates can be hydrolyzed by human intestinal microbiota leading to liberation of ZEN that implies an underestimation of the true ZEN exposure. In order to include ZEN conjugates in routine analysis, as well as for toxicological investigation reliable standards are needed. The objective of the present study was to develop a simple and economic method for biosynthesis of ZEN conjugates. Preceding experiments on the biotransformation of ZEN by Rhizopus and Aspergillus species showed a mixed metabolite formation3. Therefore, these known ZEN conjugating fungal strains were screened for their potential to selectively synthesize the ZEN derivatives ZEN-14-sulfate (Z14S),Zearalenone (ZEN) and its sulfate and glucoside conjugates have been detected in (a broad variety of) food and feed commodities1. Both conjugated derivatives are formed as part of fungal or plant secondary metabolism and thus, belong to the group of modified mycotoxins2. After consumption of contaminated foodstuff, the conjugates can be hydrolyzed by human intestinal microbiota leading to liberation of ZEN that implies an underestimation of the true ZEN exposure. In order to include ZEN conjugates in routine analysis, as well as for toxicological investigation reliable standards are needed. The objective of the present study was to develop a simple and economic method for biosynthesis of ZEN conjugates. Preceding experiments on the biotransformation of ZEN by Rhizopus and Aspergillus species showed a mixed metabolite formation3. Therefore, these known ZEN conjugating fungal strains were screened for their potential to selectively synthesize the ZEN derivatives ZEN-14-sulfate (Z14S), ZEN-14-glucoside (Z14G) and ZEN-16-glucoside (Z16G). The screening was conducted by adding ZEN to liquid fungal cultures. Cultivation conditions and ZEN incubation time were varied. All media samples were analyzed for metabolite formation by HPLC-MS/MS. Z14S was exclusively formed by A. oryzae. Under optimized conditions a specific biosynthesis of Z14G by R. oryzae and Z16G by R. oligosporus was achieved. After liquid-liquid-extraction and preparative chromatographic cleanup 1H-NMR purities of ≥ 73% for Z14S, ≥ 82% for Z14G and ≥ 50% for Z16G were obtained. In addition, a consecutive biosynthesis was developed by first using Fusarium graminearum for ZEN biosynthesis on rice based liquid medium. After inactivation of Fusarium the subsequent conjugation reaction was conducted utilizing Aspergillus and Rhizopus species under the various optimized conditions. In this study an easy and cost-efficient biosynthesis for Z14S, Z14G and Z16G was developed. The developed biosynthesis could be also used for other metabolites like ZEL conjugates. Our results of the in vitro screening indicate also the formation of a ZEL-glucoside and α ZEL-sulfate as major metabolites by R. oryzae. In sum, under optimized cultivation conditions fungi can be easily utilized for a targeted and stereospecific synthesis of ZEN conjugates.zeige mehrzeige weniger

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Metadaten
Autoren/innen:Ronald Maul
Koautoren/innen:Antje Borzekowski, Tatjana Drewitz, Julia Keller, Dietmar Pfeifer, Hans-Jörg Kunte, Matthias Koch, S. Rohn
Dokumenttyp:Posterpräsentation
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2018
Organisationseinheit der BAM:1 Analytische Chemie; Referenzmaterialien
1 Analytische Chemie; Referenzmaterialien / 1.3 Strukturanalytik
1 Analytische Chemie; Referenzmaterialien / 1.7 Organische Spuren- und Lebensmittelanalytik
4 Material und Umwelt
4 Material und Umwelt / 4.1 Biologische Materialschädigung und Referenzorganismen
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Analytical standards; Food safety; Mycotoxins
Themenfelder/Aktivitätsfelder der BAM:Analytical Sciences
Analytical Sciences / Spurenanalytik und chemische Zusammensetzung
Veranstaltung:10th World Mycotoxin Forum Conference
Veranstaltungsort:Amsterdam, The Netherlands
Beginndatum der Veranstaltung:12.03.2018
Enddatum der Veranstaltung:14.03.2018
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:22.03.2018
Referierte Publikation:Nein