Occurrence of toxigenic Aspergillus flavus in commercial Bulgur wheat

Abstract

Aflatoxins are mutagenic, carcinogenic, and teratogenic mycotoxins. The objective of this work was to study the presence of aflatoxigenic Aspergillus in commercial Bulgur wheat in the city of Maringá, Paraná, Brazil. Thirty samples of commercial Bulgur wheat, acquired in the period of August 2011 to January 2012, were evaluated. The enumeration analysis showed that samples had up to 273.3 CFU of molds and 133.3 CFU of aflatoxigenic Aspergillus per gram of wheat. Forty-two monosporic isolates were obtained and identified as Aspergillus flavus. The isolates were analyzed regarding their aflatoxigenic potential by culture in coconut milk agar; hydroxide vapor exposure; chromatography; and polymerase chain reaction (PCR) targeting genes that code enzymes of the aflatoxins synthesis pathway. Some of the isolates were confirmed to be aflatoxin producers and several of them presented a genetic profile of aflatoxin synthesis. The obtained results demonstrated that Bulgur wheat A. flavus contamination is concerning. Keywords: Aspergillus flavus; aflatoxins; Bulgur wheat; PCR.Practical Application: Aflatoxicosis associated with consumption of contaminated food is a major concern due to the risk of liver cancer and other diseases. The presence of aflatoxigenic Aspergillus needs to be monitored to evaluate the potential for aflatoxin contamination in food. This study presents methods of screening for aflatoxigenic Aspergillus in commercial Bulgur wheat. In addition, this work offers methods of isolation and identification of the Aspergillus species present in food and methods for testing the aflatoxigenic potential of the isolates.

The occurrence of aflatoxigenic Aspergillus spp. in dairy cattle feed in Southern Brazil

“… 38 Multiplex and single PCR systems have been used for detection of aflatoxigenic Aspergillus isolates, performed both as conventional and real-time PCR. 17 , 23 , 25 , 26 , 29 , 39 The multiplex PCR system used in this work was already used to discriminate among aflatoxigenic and non-aflatoxigenic Aspergillus isolates. 29 , 39 This reaction used the pair of primers APA-450 and APA-1482 designed by Shapira et al, which amplifies a DNA fragment of 1032 bp of the A. parasiticus apa-2 gene, which codes for a transcription factor containing a zinc cluster DNA binding motif that activates aflatoxin B1 and B2 biosynthesis by controlling the expression of the nor-1 and ver-1 genes.…”

“…The fact that aflatoxin negative A. flavus strains presented amplification of all tested genes is intriguing, but this pattern was already reported in the literature. 23 , 26 …”

“…Approximately 300 μL of this powder was transferred to a microtube and the DNA was extracted according to the method described by Koenig et al 22 with the modifications reported by Faria et al 23 The DNA was quantified using a spectrophotometer and the final concentration was adjusted to 100 ng/μL.…”

“…Of the obtained suspension, a 100 μL aliquot (containing 9.6 × 10 5 spores) without the agar fragments was spread on Petri dishes containing malt glucose agar (MGA) [50 g/L malt extract, 50 g/L glucose, 20 g/L agar] or CMA medium. 23 , 29 The dishes were incubated at 28 °C for seven days. Only one dish was cultured and analyzed for each isolate.…”

Research on Mould and Aflatoxin Contamination Levels of Feeds Used in Trout Farms of Adana (Turkey)

“…They can easily grow anywhere as they are plenty in nature and are not prone to develop (Şahin and Korukluoğlu, 2000). They cause an unfavorable sour smell, deterioration, reduction in dry matter, nutrient and economic loss of the product that they grow on; more than that they can produce different types of mycotoxins (Maciorowski et al, 2007;Faria et al, 2017).…”