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

AbstractAflatoxins are toxic and carcinogenic secondary metabolites produced primarily by the filamentous fungiAspergillus flavus andAspergillus parasiticus and cause toxin contamination in food chain worldwide.Aspergillus oryzae andAspergillus 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 beA. sojae usingβ-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 ofaflR gene of these new isolates was sequenced. Comparison ofaflR DNA sequences of PWE,A. parasiticus andA. sojae, showed that the aflatoxigenic PWE strains had the six base insertion (CTCATG) similar to domesticatedA. 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 bothA. parasiticus andA. sojae. Concordance analysis of multi locus DNA sequences indicated that PWE strains were closely linked betweenA. parasiticus andA. sojae. T...
Source: Mycotoxin Research - Category: Toxicology Source Type: research