Location: Food and Feed Safety ResearchTitle: Secondary metabolite dereplication and phylogenetic analysis identify various emerging mycotoxins and reveal the high intra-species diversity in Aspergillus flavus
|UKA, VALDET - Ghent University
|ARROYO-MANZANARES, N - University De Granada
|NEBIJA, D - University Of Prishtina
|DE SAEGER, SARAH - Ghent University
|DIANA DI MAVUNGU, JOSE - Ghent University
Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/2019
Publication Date: 4/5/2019
Citation: Uka, V., Moore, G.G., Arroyo-Manzanares, N., Nebija, D., De Saeger, S., Diana Di Mavungu, J. 2019. Secondary metabolite dereplication and phylogenetic analysis identify various emerging mycotoxins and reveal the high intra-species diversity in Aspergillus flavus. Frontiers in Microbiology. 10:667. https://doi.org/10.3389/fmicb.2019.00667.
Interpretive Summary: Aspergillus flavus is one of the most important mycotoxigenic species due to its ability to synthesize the potent hepatocarcinogen, aflatoxin B1. In this study, we sought to identify and compare other toxic metabolites produced by more than 50 different isolates this fungus. Our findings provide evidence of many important classes of toxic A. flavus metabolites, including M aflatoxins, which are considered derivatives that form within humans and animals after consuming B aflatoxins. Both metabolic and phylogenetic analyses showed a very high degree of intra-species diversity for A. flavus. These findings contribute to our understanding about the diversity of Aspergillus section Flavi species, increasing the necessity for polyphasic approaches (morphological, metabolic, genetic, etc.) when characterizing this complex group of species.
Technical Abstract: We investigated the metabolomes of more than 50 A. flavus isolates using a secondary metabolite dereplication strategy. Accurate mass qTOF HRMS data were used to identify A. flavus metabolites, putatively by automatic dereplication, using a customized database. Afterwards, accurate mass HRMS data were combined with a careful evaluation of fragmentation spectra, to ascertain the presence of previously identified A. flavus metabolites and to establish an unambiguous identification strategy for subsequent screening work. Phylogenetic inferences based on amplicon sequencing and concatenation of several genomic loci were also undertaken to confirm morphological identifications and ascertain diversity among the isolates. We observed production of several toxic compounds from the classes of indole-tetramates, non-ribosomal peptides and indole-diterpenoids. We identified the inherent production of an aflatoxin compound (aflatoxin M) previously thought to derive only from the ingestion of B aflatoxins. Our findings also determined that an isolate morphologically identified as A. flavus that produces G aflatoxins was actually A. nomius (based on BLAST query of several genomic loci), thereby supporting our belief that fungal identifications should be multi-faceted.