U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Https

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

PubAg

Main content area

First report of an atypical new Aspergillus parasiticus isolates with nucleotide insertion in aflR gene resembling to A. sojae

Author:
Sui Sheng T. Hua, Dan E. Parfitt, Siov Bouy L. Sarreal, Bertram G. Lee, Delilah F. Wood
Source:
Mycotoxin research 2018 v.34 no.2 pp. 151-157
ISSN:
0178-7888
Subject:
Aspergillus flavus, Aspergillus oryzae, Aspergillus parasiticus, Aspergillus sojae, DNA, GRAS substances, Pistacia vera, aflatoxins, databases, food chain, food safety, fungi, genes, image analysis, koji, loci, miso, nucleotide sequences, orchards, pistachios, sake, secondary metabolites, spores, toxicity, tubulin, California
Abstract:
Aflatoxins are toxic and carcinogenic secondary metabolites produced primarily by the filamentous fungi Aspergillus flavus and Aspergillus parasiticus and cause toxin contamination in food chain worldwide. Aspergillus oryzae and Aspergillus sojae are highly valued as koji molds in the traditional preparation of fermented foods, such as miso, sake, and shoyu. Koji mold species are generally perceived of as being nontoxigenic and are generally recognized as safe (GRAS). Fungal isolates were collected from a California orchard and a few were initially identified to be A. sojae using β-tubulin gene sequences blasted against NCBI data base. These new isolates all produced aflatoxins B₁, B₂, G₁, and G₂ and were named as Pistachio Winter Experiment (PWE) strains. Thus, it is very important to further characterize these strains for food safety purposes. The full length of aflR gene of these new isolates was sequenced. Comparison of aflR DNA sequences of PWE, A. parasiticus and A. sojae, showed that the aflatoxigenic PWE strains had the six base insertion (CTCATG) similar to domesticated A. sojae, but a pre-termination codon TGA at nucleotide positions 1153–1155 was absent due to a nucleotide codon change from T to C. Colony morphology and scanning microscopic imaging of spore surfaces showed similarity of PWE strains to both A. parasiticus and A. sojae. Concordance analysis of multi locus DNA sequences indicated that PWE strains were closely linked between A. parasiticus and A. sojae. The finding documented the first report that such unique strains have been found in North America and in the world.
Agid:
5929172
Handle:
10113/5929172