Aflatoxin Contamination Of Grain Research Articles

Assessing aflatoxin safety awareness among grain and cereal sellers in greater Accra region of Ghana: A machine learning approach

Studies have established high prevalence of aflatoxin contamination in grains and cereals produced in Ghana. Mitigation strategies have focused mainly on capacity building for farmers, agricultural extension officers, bulk distributors and processors to the detriment of the market women who act as the final link between consumers and producers. This study used supervised machine learning algorithms by means of Classification and Regression Trees (CART) to investigate aflatoxin knowledge and awareness of market women in Greater Accra Region of Ghana. A cross-sectional survey and probability sampling methods were employed for data collection. Ninety-two (92%) of participants had never heard about aflatoxins and yet, 62% reported that they usually observe mould growth in their cereals/grains. Unsurprisingly, 97% of participants indicated that they had no knowledge of the aflatoxin bill passed by the government of Ghana parliament. Despite participants not being aware of aflatoxin menace, the percent correctness of their aflatoxin safety measure score was 40%. A regression tree algorithm showed that, participant's ethnic group was the most significant parameter to consider regarding their aflatoxin safety knowledge. Their educational background and age were 95.5% and 72.5% as significant as their ethnic group. A classification tree algorithm showed that, educational level was the most significant parameter to consider when it comes to sorting of grains/cereals. Their ethnic group and marital status were 92.4% and 89.3% as important as educational level. It is therefore imperative for the Ghana government to extend sensitization and awareness programs to these market women, targeting the uneducated and specific age and ethnic groups.

Simultaneous detection of Aspergillus moulds and aflatoxin B1 contamination in rice by laser induced fluorescence spectroscopy

Mould and aflatoxin contamination remains a serious threat to food quality and safety. In this study, simultaneous detection of Aspergillus moulds and aflatoxin B1 (AFB1) contamination in rice was investigated by laser induced fluorescence (LIF) technology for the first time. Different Aspergillus strains belong to toxigenic and non-toxigenic species were artificially inoculated in rice samples and storage for a period of time to evolve into various mould and AFB1 infection levels. Spectral analysis and principal component analysis (PCA) indicated that mould activity could be monitored by LIF spectroscopy. Subsequently, three classification methods based on linear and non-linear algorithms were established to classify rice samples in terms of the type of infected mould, mould infection level as well as AFB1 concentration. The best correct classified rate obtained achieved 97% with false positive rates less than 2%. In addition, the discrimination towards rice flour samples performed better than kernel samples. These findings verify the potential of LIF spectroscopy as a rapid and non-destructive way for sensitive and effective detection of mould and aflatoxin contamination in grains without any complicated pre-processing.

Community knowledge and awareness of aflatoxin in dietary staples in rural Busia county, Kenya: A mixed methods study

Aflatoxins are an important food safety challenge globally and in Kenya. Understanding a community’s knowledge, perception and practices is instrumental to improvement of aflatoxin control measures. Creating awareness on the causes of contamination and mitigation options could improve aflatoxin mitigation. This study aimed to map out dietary staples, establish drivers of food choices, describe knowledge and perceptions on aflatoxin and post-harvest grain management practices and use among the communities in Busia County in order to guide future evidence-based aflatoxin prevention and public health interventions. A household survey was conducted in 40 villages, and participants were selected using stratified systematic sampling in three sub-counties in rural Busia County. The survey was complemented and triangulated with a qualitative study component. Focus Group Discussions with sixty women and sixteen semi- structured interviews with nine men and seven women were conducted. Both descriptive and statistical analysis of data were performed. The results showed variability in household diversity scores and maize was observed as the community staple. While both younger and older participants were able to identify spoilt grains, they demonstrated limited knowledge and awareness of aflatoxin. Participants were not aware that seemingly clean grains could be colonized by aflatoxin as they only associated spoilage with discoloration and bitter taste of flour. Study participants were also not aware of the aflatoxin pathways to exposure as they used the spoilt grains in feeding chicken, making animal feed and local brew. Appropriate disposal methods of aflatoxin contaminated food were not known. The knowledge gap was attributed to lack of awareness creation and sensitization by the relevant government ministries. For effective control and prevention of aflatoxin contamination, farmers and traders need to be aware of the causes of aflatoxin contamination of grains, available mitigation options and health risks attributable to aflatoxin exposure in order to self-regulate. Ministries of health and agriculture, through their public health officers, community health workers and agricultural extension officers respectively need to collaborate and spearhead awareness creation among communities and institute food surveillance systems in Busia County.

Current and promising strategies to prevent and reduce aflatoxin contamination in grains and food matrices

Mycotoxins are secondary metabolites produced by filamentous fungi that colonise various crops around the world and cause major damage to the agro-industrial sector on a global scale. Considering the estimative of population growth in the next decades, it is of fundamental importance the implementation of practices that help prevent the economics and social impacts of aflatoxin contamination. Even though various approaches have been developed – including physical, chemical and biological approaches – there is not yet one that strikes a balance in terms of safety, food quality and cost, especially when considering large scale application. In this review, we present a compilation of advantages and disadvantages of different strategies for prevention and reduction of aflatoxin contamination. Biological approaches represent the trend in innovations mainly due to their specificity and versatility, since it is possible to consider the utilisation of whole microorganisms, culture supernatants, purified enzymes or even genetic engineering. However, challenges related to improvement of the efficiency of such methods and ensuring safety of treated foods still need to be overcome.

Pre-harvest silk treatment with Trichoderma harzianum reduces aflatoxin contamination in sweetcorn

One of the most promising management tools to reduce mycotoxins in food and feed is the pre-harvest biological control of mycotoxigenic fungi using microbes. The goal of this investigation was to evaluate the potential of a stain of Trichoderma harzianum, T77, for control of Aspergillus flavus on sweetcorn. Under greenhouse and field conditions, T. harzianum was applied as a pre-harvest spray treatment to silks of sweetcorn plants at 1, 3, 6, 8, 10, 12 and 14 days post-midsilk. Toxigenic A. flavus was spray inoculated as a conidial suspension (103 spores ml−1) onto silks at 2, 4, 7, 9, 11 and 13 days post-midsilk. Percentage kernel infection, disease ratings, ELISA and HPLC analyses were used to quantify A. flavus infection and aflatoxin contamination. There was a significant reduction in toxigenic A. flavus infection and aflatoxin contamination after silk spray treatments with T77 at 10 and 12 days post-midsilk. In vitro dual culture bioassays and ultrastructural studies using environmental scanning electron microscopy revealed antibiosis and mycoparasitism are the probable modes of action. It thus can be seen that pre-harvest spray treatment of sweetcorn at the silk growth stage can reduce the level of A. flavus contamination of grain. An integrated approach consisting pre-harvest biological control using selected strains of T. harzianum in conjunction with other post-harvest management strategies could reduce A. flavus infection and aflatoxin contamination in grain.

English

Aflatoxin contamination impinges on grain quality worldwide. The causative agent, Aspergillus spp. colonizes grain in the field down to postharvest stages in storage where they may produce toxins. Kenya has experienced recurring cases of aflatoxicosis in Eastern region especially during periods of maize grain deficit. The risk of chronic exposure has not been widely studied. Therefore, seasonal variation in abundance and species composition of toxigenic Aspergillus in maize and soils of Eastern Kenya was investigated. Samples were obtained from farmers, two months after the first (May) and second (December) harvest seasons. Aspergillus spp. were isolated from maize and soil samples by direct and dilution plate techniques respectively on Czapek Dox Agar (CZ) and thereafter sub-cultured on potato dextrose agar (PDA). Positive identification was done using culture-morphological and microscopic characteristics in PDA media. The ammonium vapour test was used to screen for the putative toxigenic strains. A total of 229 Aspergillus spp. cultures were obtained (55% -maize, 45% -soil). Eleven Aspergillus sp. were identified: Aspergillus niger, Aspergillus flavus, Aspergillus clavatus, Aspergillus awamori, Aspergillus parasiticus, Aspergillus ochraceus, Aspergillus candidus, Aspergillus ustus, Aspergillus niveus, Aspergillus terreus and Aspergillus wentii. Of these 41 (18 %) were potentially toxigenic while the rest were putatively atoxigenic. Out of the 41 toxigenic isolates, 22 were from maize. The first season had 15 (68.2%) toxigenic maize isolates while 7 (31.8%) were from the second season. Generally, there were more fungal isolates in the first season (54.1%) than the second one (45.9%) while Aspergillus niger was the most abundant in both seasons. Such variation in fungal abundance supports the hypothesis that aflatoxin contamination of grain may vary seasonally but that remains to be unravelled and herein, a contrary opinion was presented. Key words: Aflatoxin, mycotoxin, Aspergillus, maize, soil.

Environmental distribution and genetic diversity of vegetative compatibility groups determine biocontrol strategies to mitigate aflatoxin contamination of maize by Aspergillus flavus.

Maize infected by aflatoxin-producing Aspergillus flavus may become contaminated with aflatoxins, and as a result, threaten human health, food security and farmers' income in developing countries where maize is a staple. Environmental distribution and genetic diversity of A. flavus can influence the effectiveness of atoxigenic isolates in mitigating aflatoxin contamination. However, such information has not been used to facilitate selection and deployment of atoxigenic isolates. A total of 35 isolates of A. flavus isolated from maize samples collected from three agro-ecological zones of Nigeria were used in this study. Ecophysiological characteristics, distribution and genetic diversity of the isolates were determined to identify vegetative compatibility groups (VCGs). The generated data were used to inform selection and deployment of native atoxigenic isolates to mitigate aflatoxin contamination in maize. In co-inoculation with toxigenic isolates, atoxigenic isolates reduced aflatoxin contamination in grain by > 96%. A total of 25 VCGs were inferred from the collected isolates based on complementation tests involving nitrate non-utilizing (nit(-)) mutants. To determine genetic diversity and distribution of VCGs across agro-ecological zones, 832 nit(-) mutants from 52 locations in 11 administrative districts were paired with one self-complementary nitrate auxotroph tester-pair for each VCG. Atoxigenic VCGs accounted for 81.1% of the 153 positive complementations recorded. Genetic diversity of VCGs was highest in the derived savannah agro-ecological zone (H = 2.61) compared with the southern Guinea savannah (H = 1.90) and northern Guinea savannah (H = 0.94) zones. Genetic richness (H = 2.60) and evenness (E5 = 0.96) of VCGs were high across all agro-ecological zones. Ten VCGs (40%) had members restricted to the original location of isolation, whereas 15 VCGs (60%) had members located between the original source of isolation and a distance > 400 km away. The present study identified widely distributed VCGs in Nigeria such as AV0222, AV3279, AV3304 and AV16127, whose atoxigenic members can be deployed for a region-wide biocontrol of toxigenic isolates to reduce aflatoxin contamination in maize.

Inhibitory effect of eugenol on aflatoxin B1 production in Aspergillus parasiticus by downregulating the expression of major genes in the toxin biosynthetic pathway.

Aflatoxin contamination of grains and agro-products is a serious food safety issue and a significant economic concern worldwide. In the present study, the effects of eugenol on Aspergillus parasiticus growth and aflatoxin production were studied in relation to the expression of some essential genes involved in aflatoxin biosynthetic pathway. The fungus was cultured in presence of serial two-fold concentrations of eugenol (15.62-500 μg mL(-1)) for 3 days at 28 °C. Mycelia dry weight was determined as an index of fungal growth, while aflatoxin production was assessed by high performance liquid chromatography. The expression of aflatoxin biosynthetic genes including ver-1, nor-1, pksA, omtA and aflR were evaluated by real-time PCR. Eugenol strongly inhibited A. parasiticus growth in the range of 19.16-95.83 % in a dose-dependent manner. Aflatoxin B1 production was also inhibited by the compound in the range of 15.07-98.0 %. The expressions of ver-1, nor-1, pksA, omtA and aflR genes were significantly suppressed by eugenol at concentrations of 62.5 and 125 μg mL(-1). These results indicate that eugenol may be considered as a good candidate to control toxigenic fungal growth and the subsequent contamination of food, feed and agricultural commodities by carcinogenic aflatoxins.

Peanut Resistance Gene Expression in Response to Aspergillus flavus Infection During Seed Germination

AbstractAspergillus flavus produces potent mutagenic and carcinogenic polyketide‐derived secondary metabolites known as aflatoxins. Development of host plant resistance in peanut and other crops is the most environmentally friendly and cost‐effective method to eliminate the serious problem of aflatoxin contamination in grains. To confirm that putative peanut genes identified in a previous microarray study were involved in peanut resistance to A. flavus infection, 14 genes were selected for further investigation through real‐time PCR. The results revealed diverse patterns of gene expression during seed germination after A. flavus inoculation. Based on the expression levels and the relative‐expression patterns over a 7‐day period, the 14 host genes could be classified into six different groups belonging to three main biochemical and genetic defence processes of lipid metabolism, oxidative signalling and cell‐wall synthesis during counter‐attack. A network of gene expression patterns was activated in sequential order in response to A. flavus invasion in both resistant and susceptible peanut lines during seed germination. Understanding gene expression patterns in peanut will be useful to breeders and other scientists interested in incorporating genetic resources of resistance against A. flavus into peanut germplasm and/or commercial cultivars via conventional and/or molecular methods.

Agroecological Zone is Associated with Stunting in Children Aged 12–59 Months in Kenya

The objective of this study was to investigate the relationship between agroecological zones (AEZ) and stunting in children aged 12–59 months in Kenya. Kenya has 7 AEZ, ranging from humid to very arid. Aflatoxin exposure has been associated with child stunting and studies have found that aflatoxin contamination of grain varies by AEZ with aflatoxin highest in AEZ with moderate rainfall (600–1000mm). GPS data from the 2009 Kenya Demographic and Health Survey and an AEZ GIS map of Kenya were used to calculate AEZ for children (n=3015 children). Mean HAZ was −1.58 (range= −1.44 in very arid to −1.93 in semi‐arid). A hierarchical linear model was used to predict height‐for‐age Z score (HAZ) and child stunting (z<‐2). After controlling for known predictors of child stunting (sex, diet diversity, wealth index, and maternal height, weight and education), there were no significant differences in HAZ among zones except for the semi‐arid zone (rainfall ranging from 450–900mm) where children are 47% more likely to be stunted (OR = 1.47, CI (1.063,2.033)) with a difference of almost 0.4 Z scores (ΔHAZ =‐0.358 compared to mean HAZ in other zones, P= 0.011). These findings suggest that a characteristic of AEZ‐potentially aflatoxin contamination of grain‐is associated with child stunting in Kenya.Grant Funding Source : None

Monitoring the Expression of Maize Genes in Developing Kernels under Drought Stress using Oligo‐microarray

Preharvest aflatoxin contamination of grain grown on the US southeastern Coast Plain is provoked and aggravated by abiotic stress. The primary abiotic stress is drought along with high temperatures. The objectives of the present study were to monitor gene expression in developing kernels in response to drought stress and to identify drought-responsive genes for possible use in germplasm assessment. The maize breeding line Tex6 was used, and gene expression profiles were analyzed in developing kernels under drought stress verses well-watered conditions at the stages of 25, 30, 35, 40, 45 d after pollination (DAP) using the 70 mer maize oligo-arrays. A total of 9 573 positive array spots were detected with unique gene IDs, and 7 988 were common in both stressed and well-watered samples. Expression patterns of some genes in several stress response-associated pathways, including abscisic acid, jasmonic acid and phenylalanine ammonia-lyase, were examined, and these specific genes were responsive to drought stress positively. Real-time quantitative polymerase chain reaction validated microarray expression data. The comparison between Tex6 and B73 revealed that there were significant differences in specific gene expression, patterns and levels. Several defense-related genes had been downregulated, even though some defense-related or drought responsive genes were upregulated at the later stages.

Aflatoxin accumulation and kernel infection of maize hybrids inoculated with Aspergillus flavus and Aspergillus parasiticus

Over a three year period, we compared aflatoxin accumulation and kernel infection in maize hybrids inoculated with Aspergillus flavus isolate NRRL 3357, A. flavus isolate NRRL 19772, Aspergillus parasiticus isolate NRRL 6111, and all combinations of these isolates. Maize hybrids were inoculated with the Aspergillus strains using the side-needle technique at 7 days after midsilk (50% of the plants had silks emerged). Aspergillus kernel infection and aflatoxin contamination were determined at ca. 63 days after midsilk. A. flavus isolate 3357 induced high levels of aflatoxin contamination in the maize grain which was similar to levels found when this isolate was combined with the other two Aspergillus isolates. Kernel infection levels were higher in one hybrid when a combination of isolates including isolate 3357 was used. A. flavus isolate 3357 has been used to evaluate maize germplasm for aflatoxin resistance in the south-eastern USA for over 30 years. Our studies determined that inoculating plants with A. flavus isolate 3357 alone was sufficient for inducing aflatoxin contamination in grain at our location. A combination of A. flavus isolates which include isolate 3357 might be more effective in increasing levels of kernel infection and could also induce higher levels of aflatoxin at locations that do not favour disease development.

Preharvest aflatoxin contamination of corn and other grain crops grown on the U.S. Southeastern Coastal Plain

Preharvest aflatoxin contamination of grain grown on the U.S. Southeastern Coastal Plain is provoked and aggravated by both biotic and abiotic stress factors that influence infection by the Asperigillus group. Asperigillus flavus, Link ex Fr., is one of the principal toxigenic fungi of summer grains grown in the region, and the hot, humid weather patterns along with suboptimal summer rainfall favor the development of this organism. An array of arthropod species also contributes to the dispersal of this fungus as they attack and feed on the developing grain. Research on summer grains grown on the Coastal Plain has the expressed goal of reducing, and perhaps eliminating aflatoxin contamination in adapted germplasm using classical crop improvement methods to deploy host plant resistance. This research is complimented and enhanced by molecular techniques that have proven invaluable in the identification and development of superior germplasm. It also emphasizes the need to fully understand the biological interactions between fungus, arthropods, crops, and the environmental conditions that govern the aflatoxin contamination. Alternative cropping systems that avoid contamination are also integrated into this summary of this research progress.

Distribution and toxigenicity of Aspergillus species isolated from maize kernels from three agro-ecological zones in Nigeria

Maize samples were collected during a survey in three agro-ecological zones in Nigeria to determine the distribution and aflatoxin-producing potential of members of Aspergillus section Flavi. The three agro-ecological zones were, Derived Savannah (DS) and Southern Guinea Savannah (SGS) in the humid south and North Guinea Savannah (NGS) in the drier north. Across agro-ecological zones, Aspergillus was the most predominant fungal genera identified followed by Fusarium with mean incidences of 70 and 24%, respectively. Among Aspergillus, A. flavus was the most predominant and L-strains constituted > 90% of the species identified, while the frequency of the unnamed taxon S BG was < 3%. The incidence of atoxigenic strains of A. flavus was higher in all the districts surveyed except in the Ogbomosho and Mokwa districts in DS and SGS zones, respectively, where frequency of toxigenic strains were significantly ( P < 0.05) higher than that of atoxigenic strains. The highest and lowest incidence of aflatoxin positive samples was recorded in the SGS (72%) and NGS (20%), respectively. Aflatoxin contamination in grain also followed a similar trend and the highest mean levels of B-aflatoxins were detected in maize samples obtained from Bida (612 ng g − 1 ) and Mokwa (169 ng g − 1 ) districts, respectively, in the SGS. Similarly, the highest concentrations of G-aflatoxins were detected in samples from Akwanga district in the SGS with a mean of 193 and 60 ng g − 1 , respectively. When agro-ecological zones were compared, B-aflatoxins were significantly ( P < 0.05) higher in SGS than in NGS, and intermediate in maize samples from the DS agro-ecological zone.

Comparison of Aspergillus Ear Rot and Aflatoxin Contamination in Grain of High-Oil and Normal-Oil Corn Hybrids

High-oil corn (Zea mays L.) grain is a valuable component of feed for monogastric livestock. One method of increasing the concentration of oil in corn grain is the TopCross method. With TopCross, ears of a cytoplasmic male-sterile, normal-oil hybrid are pollinated by a male-fertile, high-oil synthetic hybrid. The concentration of oil in the resulting grain is increased because of xenia effects. Kernels of high-oil corn typically have a larger germ and a smaller endosperm than kernels of comparable normal hybrids. The growth of Aspergillus flavus Link:Fr within germ tissue has been reported to be more extensive than that on the whole corn kernel; therefore, the severity of Aspergillus ear rot could be more extensive and aflatoxin concentrations could be higher in high-oil grain produced by TopCross than in grain with a lower concentration of oil. The objective of this study was to compare Aspergillus ear rot severity levels and aflatoxin concentrations in the grains of hybrids crossed with high-oil or normal-oil pollinators. Fifteen hybrids were evaluated in 1998 and 1999 in Urbana, Ill. Primary ears were inoculated with A. flavus and evaluated for susceptibility to Aspergillus ear rot and aflatoxin production in grain. Concentrations of aflatoxin and oil in corn kernels were significantly higher for high-oil hybrids than for normal-oil hybrids; however, ear rot severity was unaffected by the type of pollinator. These results suggest that grain from high-oil hybrids is at greater risk for aflatoxin contamination during some growing seasons.

Evaluation of Corn Genotypes for Resistance to Aspergillus Ear Rot, Kernel Infection, and Aflatoxin Production

Campbell, K. W., and White, D. G. 1995. Evaluation of corn genotypes for resistance to Aspergillus ear rot, kernel infection, and aflatoxin production. Plant Dis. 79:1039-1045. Resistance of corn (Zea mays L.) hybrids and inbreds to ear rot, kernel infection, and aflatoxin contamination caused by Aspergillus flavus was evaluated following inoculation. Thirty-five F 1 hybrids from crosses of selected inbreds with the susceptible inbreds B73 and/or Mo17 were evaluated for 3 years in Illinois. Fifteen of the F 1 hybrids also were evaluated in Mississippi. Resistant and susceptible inbreds per se also were evaluated for 2 years in Illinois. Inbreds Tex6, Y7, and Mp420, and the F 1 hybrids with these inbreds, consistently had the greatest resistance to Aspergillus ear rot, kernel infection, and aflatoxin production in the Illinois environment. Grain of the F 1 hybrids with these inbreds also had less aflatoxin in Mississippi. Pearson and Spearman rank correlation coefficients indicated that Aspergillus ear rot ratings provided a more accurate estimate of aflatoxin contamination of grain than did kernel infection. From evaluations of the F 1 hybrids and the inbred parents per se, inbreds were identified that may contain alleles for resistance not found in B73 and/or Mo17.

Aflatoxin in Corn Hybrids Field Inoculated with Aspergillus flavus

AbstractCorn (Zea mays L.) genotypes with resistance to Aspergillus flavus Link ex Fr. are needed to reduce aflatoxin contamination of grain. The primary objective of this study was to determine if the pinbar inoculation technique was effective in separating hybrids for resistance and susceptibility to kernel infection by A. flavus and aflatoxin contamination of the grain at a number of locations, but other inoculation techniques were evaluated at individual locations. Two single crosses, Mo18W × Mp313E and SC54 × Tx601, previously classified as resistant to kernel infection by A. flavus and two susceptible crosses, Mp68:616 × SC212M and GT106 × T202, were used. We found that hybrids previously classified as resistant to kernel infection by A. flavus had fewer kernels infected and lower aflatoxin concentration in the corn grain at harvest. However, these differences were not significant at all locations. Over six locations, resistant hybrids contained 58% less aflatoxin in the grain and 41% fewer infected kernels than susceptible hybrids. In addition to the pinbar, the side‐needle, and to a lesser extent the knife inoculation technique, differentiated hybrid response to ear inoculation with A. flavus.

Aflatoxin contamination in grains from the Pacific coast in Guatemala and the effect of storage upon contamination.

Aflatoxin contamination in grains from the Pacific coast in Guatemala and the effect of storage upon contamination.

Aflatoxin Contamination of Cottonseed

To the Editor.— Stephanie C. Crocco, PhD (242:548, 1979), of the American Medical Association Department of Food and Nutrition gave, in the QUESTIONS AND ANSWERS section, a summary of the current situation regarding aflatoxin contamination of grain. She has, however, failed to mention another source of aflatoxin introduction into the human food chain: the use of aflatoxin-contaminated cottonseed as feed for dairy cattle. Last year, aflatoxin appeared in high levels in milk in Arizona because of the use of this feed, and a major control effort is underway to prevent such an occurrence in the future. Physicians practicing in cotton-producing areas should be aware of this possible additional source of aflatoxin contamination in food.

Aflatoxin contamination in grains and grain products during the dry season in Guatemala.

Aflatoxin contamination in grains and grain products during the dry season in Guatemala.