African Journal of Biotechnology Occurrence of aflatoxin contamination in maize kernels and molecular characterization of the producing organism, Aspergillus (original) (raw)
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Toxins, 2019
Highly toxigenic strains of Aspergillus flavus have been reported to frequently contaminate maize, causing fatal aflatoxin poisoning in Kenya. To gain insights into the environmental and genetic factors that influence toxigenicity, fungi (n = 218) that were culturally identified as A. flavus were isolated from maize grains samples (n = 120) from three regions of Kenya. The fungi were further characterized to confirm their identities using a PCR-sequence analysis of the internal transcribed spacer (ITS) region of rDNA which also revealed all of them to be A. flavus. A subset of 72 isolates representing ITS sequence-based phylogeny cluster and the agroecological origin of maize samples was constituted for subsequent analysis. The analysis of partial calmodulin gene sequences showed that the subset consisted of A. flavus (87%) and Aspergillus minisclerotigenes (13%). No obvious association was detected between the presence of seven aflatoxin biosynthesis genes and fungal species or reg...
Food Microbiology, 2014
Aflatoxins are highly toxic carcinogens that contaminate crops worldwide. Previous studies conducted in Nigeria and Ghana found high concentrations of aflatoxins in pre-and post-harvest maize. However, little information is available on the population structure of Aspergillus Sect. Flavi in West Africa. We determined the incidence of Aspergillus Sect. Flavi and the level of aflatoxin contamination in 91 maize samples from farms and markets in Nigeria and Ghana. Aspergillus spp. were recovered from 61/91 maize samples and aflatoxins B 1 and/or B 2 occurred in 36/91 samples. Three samples from the farms also contained aflatoxin G 1 and/or G 2. Farm samples were more highly contaminated than were samples from the market, in terms of both the percentage of the samples contaminated and the level of mycotoxin contamination. One-hundred-and-thirty-five strains representative of the 1163 strains collected were identified by using a multilocus sequence analysis of portions of the genes encoding calmodulin, btubulin and actin, and evaluated for aflatoxin production. Of the 135 strains, there were 110 e Aspergillus flavus, 20 e Aspergillus tamarii, 2 e Aspergillus wentii, 2 e Aspergillus flavofurcatus, and 1 e Aspergillus parvisclerotigenus. Twenty-five of the A. flavus strains and the A. parvisclerotigenus strain were the only strains that produced aflatoxins. The higher contamination of the farm than the market samples suggests that the aflatoxin exposure of rural farmers is even higher than previously estimated based on reported contamination of market samples. The relative infrequency of the A. flavus S BG strains, producing small sclerotia and high levels of both aflatoxins (B and G), suggests that long-term chronic exposure to this mycotoxin are a much higher health risk in West Africa than is the acute toxicity due to very highly contaminated maize in east Africa.
Aspergillus flavus maize colonization leads to crop contamination by toxic secondary metabolites and carcinogens called aflatoxins (AF); it has negative effects in public health and has caused economic losses in agricultural activities. Eleven genotypes of immature maize grain frequently used in Mexico were inoculated in vitro with two indigenous toxigenic strains of A. flavus. The size of inoculum, temperature, humidity and presence of other phytopathogens were assessed. Genotypes Popcorn, C-526, Garst 8366, As910 and 30G40 showed resistance to rating of fungal colonization (FC) and AF accumulation, while 3002W, 30R39, Creole, C-922, HV313 and P3028W genotypes were less resistant. AFB 1 had the highest concentrations (26.1 mg/kg ± 14.7 mg/kg), while AFB 2 , AFG 1 and AFG 2 showed only residual concentrations 1.6, 2.0 and 4.0 μg/kg, respectively. Concerning FC and AF, there were significant differences (P < 0.01) between strains and genotype. Both strains showed significant association (P < 0.01) between FC and the concentrations of AFB 1 and AFB 2 (R 2 : 99.5% and 93.2%; 87.2% and 73.2%, respectively). Results suggest that the level of resistance to fungus infection and AF accumulation is related to maize genotype. It emphasizes the relevance of developing A. flavus resistant maize genotypes as an alternative to control contamination in foodstuff intended for human and animal consumption. proteins and 20% of the calories in diets. Furthermore, in developing countries such as Latin America, Africa and Asia, maize is a staple food and occasionally is the only protein source in their diets . Around 78% of maize samples are contaminated with AF [7]. Economic losses attributed to AF contamination are large , mainly in developing countries that lack the appropriate regulations for the control of mycotoxin contaminated foods . In Mexico, the presence of maize contaminated with A. flavus strains has also been documented . This is relevant due to the high national consumption of maize (20 million t/year) as well as per capita (329 g daily). In addition, the use of maize in animal feed is increasing,
Quality Assurance and Safety of Crops & Foods, 2017
The present study was conducted to study the role of mould/fungal occurrence on aflatoxin build-up in maize grains and correlation between toxigenic and genetic variability present among isolates of Aspergillus flavus obtained from maize grain samples. Eighty-six maize samples were collected from farmer's fields from various locations among the four maize growing agro-ecological zones of India. Among the microflora of maize grains studied, Aspergillus was the most predominant mould identified. Location Karnal (Haryana) was most sensitive to mould infection; 56.2% of samples), exhibited >20 μg/kg aflatoxin B 1 (AFB 1). On the other hand, Begusarai (Bihar) proves to be a less sensitive area for aflatoxin contamination with 90% of samples exhibiting <20 μg/kg AFB 1. Varied isolates of A. flavus from grain samples were established in culture media and studied for toxigenic variability. In vitro high level variability (8,116.61-0.21 μg/kg) for aflatoxin production potential was found among these isolates. Random amplified polymorphic DNA (RAPD) analysis using 35 OPERON random primers was used to study the correlation between toxigenic and genetic variability. The study exhibited partial relationship between RAPD dendrogram and geographic origin of these isolates, while no correlation was found between genetic variability and toxin production ability among A. flavus isolates studied. Also, three atoxigenic isolates of A. flavus were identified, viz. AF-9, AF-36, and AF-39, endemic to India from the Bihar, Haryana, and Delhi regions, respectively. These strains will need further validation.
Thirty-four Aspergillus flavus isolates were recovered from sorghum seeds sampled across five states in India. Our study included (1) species confirmation through PCR assay, (2) quantification of total aflatoxin concentrations by the indirect competitive-ELISA (ic-ELISA) method, and (3) analysis of molecular diversity among the A. flavus isolates using b-tubulin, ITS, and ISSR markers. Among the isolates studied, 28 were found to be positive for the production of aflatoxins. ITS and b-tubulin phylogenetic analysis segregated the A. flavus sample population into two major groups or clades with little to no subdivision based on geography. In contrast, ISSR analysis also separated the A. flavus isolates into two main clusters, showing a distance of 0.0–0.5, with one cluster exhibiting a high level of diversity though no geographic or chemotype subdivision could be observed. The majority of sampled A. flavus isolates were highly toxigenic, and also highly diversified in terms of toxin-producing potential in-vitro. Genetic diversity among the sorghum isolates of A. flavus further warrants the development of appropriate farming management practices as well as improved aflatoxin detection measures in India.
Genetics and Molecular Research, 2013
An Aspergillus population (67 strains), isolated from maize in 2003, during the first outbreak of aflatoxin contamination documented in Northern Italy, was characterised according to gene sequencing data. All strains were identified as A. flavus by sequencing of β-tubulin and calmodulin gene fragments. Furthermore, the strains were analysed for the presence of seven aflatoxin biosynthesis genes in relation to their capability to produce aflatoxin B 1 , targeting the regulatory genes aflR and aflS, and the structural genes aflD, aflM, aflO, aflP, and aflQ. The strains were placed into four groups based on their patterns of amplification products: group I (40 strains) characterised by presence of all seven amplicons; groups II (two strains) and III (nine strains), showing four (AflM, aflP, aflO, and aflQ) and three (aflO, aflP, aflQ) amplicons, respectively; and group IV (16 strains) characterised by total absence of PCR products. Only group I contained strains able to produce aflatoxin B 1 (37 out of 40), whereas the strains belonging to the other groups and lacking three, four or all seven PCR products were non-producers. The results obtained in this study pointed out that A. flavus was the only species responsible for aflatoxin contamination in Northern Italy in 2003, and that the aflatoxin gene cluster variability existing in populations can be useful for understanding the toxicological risk as well as the selection of biocontrol agents.
IOP Conference Series: Materials Science and Engineering
Aflatoxin is a naturally mutagenic and carcinogenic mycotoxin found in feed and food. Aflatoxin contamination on maize can affect productivity of feed and food manufacture. The purpose of this study was to obtain isolates and to understand the characteristics of aflatoxigenic Aspergillus flavus from maize on livestock feed. The study was divided into two stages: isolation and molecular identification of fungal ITS rDNA region in livestock feed obtained from Bogor, West Java. Isolation was conducted by enrichment and direct method using Dichloran-Glycerol (DG18) medium, while aflatoxin test and fungal characterization were done by CAM (Coconut Agar Medium) and selective medium of Aspergillus flavus and parasiticus (AFPA), respectively. The result showed that 9 of isolates are identified as molds (P2, P3, P4, P5, P7, P8, are green sporulated, while P1, P6, P9 are black sporulated). Aflatoxin detection on P3 and P8 isolates did not produce blue fluorescence fluid in CAM and did not form a beige ring on the back of petri. This indicated P3 and P8 did not produce aflatoxin on CAM media. Molecular identification results that P3 and P8 isolates have 100% and 99% homology with A. flavus, respectively.
Evaluation of Maize Genotypes for Resistance to Aspergillus Infection and Aflatoxin Production
Tropical Agricultural Research and Extension, 2011
Maize (Zea mays L) is one of the important food crops grown in Sri Lanka. Kernel infection of maize by Aspergillus flavus and subsequent aflatoxin production is a frequent and serious problem. Genetic resistance for A. flavus infection is the most economical and successful way of controlling infection and subsequent production of aflatoxins. Therefore, a study was undertaken in two locations at Maha Illuppallama to evaluate inbred lines and hybrids for resistance to Aspergillus infection and aflatoxin production. Artificial inoculation increased percentage kernel infection by Aspergillus compared to non-inoculated treatments. Percentage kernel infection by Aspergillus varied with genotypes and no significant relationship between percentage kernel infection and aflatoxin levels was found. Aflatoxin production in some hybrids found to be zero when artificially inoculated with virulent isolates of A. flavus. Commercial hybrids, namely NK 40, Sampath and Pacific grown in Sri Lanka showed susceptibility to aflatoxin production.
Toxins
Maize is one of the leading export products in the Republic of Serbia. As a country where economic development depends on agriculture, maize production plays a critical role as a crop of strategic importance. Potential aflatoxin contamination of maize poses a risk to food and feed safety and tremendous economic losses. No aflatoxin contamination of maize samples harvested in 2019 and 2020 in different localities in the Republic of Serbia was detected by the Enzyme-Linked Immunosorbent Assay (ELISA) test and High-Performance Liquid Chromatography (HPLC) method. On the other hand, the Cluster Amplification Patterns (CAP) analyses of the isolated Aspergillus flavus strains from 2019 maize samples confirmed the presence of key biosynthesis genes responsible for aflatoxin production. Artificial inoculation and subsequent HPLC analysis of the inoculated maize samples confirmed the high capacity of the A. flavus strains for aflatoxin production, pointing to a high risk of contamination und...