2021 FDA Science Forum
Whole Genome Sequences of 20 Aspergillus Flavus Isolates from Corn Kernels and Cornfield Soils in Louisiana
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Contributing OfficeCenter for Food Safety and Applied Nutrition
Abstract
Background:
Aspergillus flavus is an opportunistic pathogen that infects plants, animals and humans, and produces the carcinogenic mycotoxin, aflatoxin. Aflatoxin consumed in grains or milk is acutely toxic, stunts children’s growth and induces liver cancer. The fungus may also cause allergic reactions in humans and aspergillosis diseases, notably in lungs of immunocompromised people. Therefore, the occurrence of aflatoxin in the food chain is a public health concern and it is crucial to develop a method to identify this fungal contaminant in foods.
Purpose:
The aim of this study was to develop a rapid means of identifying this fungal contaminant using whole genome sequencing.
Methodology:
Aspergillus flavus populations are very diverse and may consist of many different vegetative compatibility groups (VCGs). Twenty isolates encompassing all 16 VCGs were selected for genome sequencing. After overnight growth of these isolates, mycelial pellets were collected, flash-frozen in liquid nitrogen, freeze-dried, and genomic DNA was extracted. Paired-end sequencing libraries were prepared using Nextera XT and sequenced on an Illumina Nextseq. The sequences were assembled using the SPAdes assembler v3.12.0, and the assembly quality assessment utilized QUAST.
Results:
The sequences were identified to the species level, using an MLST and custom kmer database and were submitted in NCBI under Bio Project PRJNA482816.
Conclusion:
There are only a few publicly available fungal genomes sequences from food isolates. The availability of high-quality genome sequences for fungi will allow detection and identification of these potential pathogens and creation of an accurate catalog of mycotoxins.
