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Title: Genome sequence of Aspergillus flavus NRRL 3357, a strain that causes aflatoxin contamination of food and feed

item NIERMAN, WILLIAM - J Craig Venter Institute
item Yu, Jiujiang
item FEDOROVA-ABRAMS, NATALIE - J Craig Venter Institute
item LOSADA, LILIANA - J Craig Venter Institute
item Cleveland, Thomas
item Bhatnagar, Deepak
item BENNETT, JOAN - Rutgers University
item DEAN, RALPH - North Carolina State University
item PAYNE, GARY - North Carolina State University

Submitted to: Genome Announcements
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2015
Publication Date: 4/16/2015
Citation: Nierman, W.C., Yu, J., Fedorova-Abrams, N.D., Losada, L., Cleveland, T.E., Bhatnagar, D., Bennett, J.W., Dean, R., Payne, G.A. 2015. Genome sequence of Aspergillus flavus NRRL 3357, a strain that causes aflatoxin contamination of food and feed. Genome Announcements. 3(2):e00168-15.

Interpretive Summary: Aflatoxins are natural secondary metabolites produced by the fungal mold Aspergillus flavus and A. parasiticus. Contamination of agricultural commodities by aflatoxins poses serious health hazard to animals and human beings. Due to health and food safety concern, the mechanism of aflatoxin formation and prevention of aflatoxin contamination have been investigated in great detail. Aspergillus flavus genomics such as expressed sequenced tags (EST), gene chip technologies, and whole genome sequencing strategies promises effective control strategy being developed through biotechnology. In this article, we reported the current progress of our genomics programs. Aspergillus flavus genomics will help our understanding in the mechanism of aflatoxin formation for devising strategies to reduce or eliminate aflatoxin contamination of food and feed.

Technical Abstract: Aflatoxin contamination of food and livestock feed results in significant annual crop losses internationally. Aspergillus flavus is the major fungus responsible for this loss. Additionally, A. flavus is the second leading cause of aspergillosis in immune compromised human patients. Here we report the genome sequence of strain NRRL 3357. Genome announcement. Filamentous fungi destroy about 10% of the world’s crop harvest by contaminating food and livestock feed with mycotoxins. Aspergillus flavus in particular produces aflatoxins, which are the most potent naturally-produced liver carcinogens. The toxins are responsible for significant health issues especially in developing countries, where food contamination is not monitored. In the U.S. alone, direct losses from aflatoxins are estimated at $240 million annually. Aspergillus flavus produces aflatoxins B1 and B2 and causes aflatoxin contamination of pre-harvest crops and post-harvest grains during storage (1). The establishment of the aflatoxin biosynthesis pathway and the identification of biosynthesis gene clusters in A. flavus has been accomplished (2). The genome sequence of NRRL 3357 has resulted in genome based efforts to understand the regulation of aflatoxin biosynthesis in order to discover new control strategies for the management of aflatoxin contamination (3). The genome sequence of A. flavus NRRL 3357 was determined using the whole genome shotgun method as described (4). Random shotgun libraries of 2-3 Kb, and 8-12 Kb, insert sizes were constructed from genomic DNA; DNA template was prepared for high-throughput sequencing using the ABI 3730XL instrument. Sequence reads were assembled using Celera Assembler. Protein-coding genes were annotated using the JCVI eukaryotic annotation pipeline as described (5). Paired-end sequence reads provided 5X genome coverage which was assembled into 2,761 scaffolds ranging in size from 4.5 Mbp to 200 bp. The 16 largest scaffolds contained 91% of the genome. The genome size is just under 40Mbp. The number of predicted protein coding genes is 13,485. We determined the number of secondary metabolite biosynthetic gene clusters in the genome using the informatics tool SMURF (6). Fifty six putative clusters were found for this strain suggesting that the fungus is capable of producing a great many more compounds than just the aflatoxins.