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Toxins Jan 2022The inhibitory action of 20 antagonistic isolates against the aflatoxigenic isolate ITEM 9 (Af-9) and their efficacy in reducing aflatoxin formation in vitro were...
The inhibitory action of 20 antagonistic isolates against the aflatoxigenic isolate ITEM 9 (Af-9) and their efficacy in reducing aflatoxin formation in vitro were examined. Production of metabolites with inhibitory effect by the isolates was also investigated. Antagonistic effect against Af-9 was assessed by inhibition of radial growth of the colonies and by fungal interactions in dual confrontation tests. A total of 8 out of 20 isolates resulted in a significant growth inhibition of 3-day-old cultures of Af-9, ranging from 13% to 65%. A total of 14 isolates reduced significantly the aflatoxin B (AfB) content of 15-day-old Af-9 cultures; 4 were ineffective, and 2 increased AfB. Reduction of AfB content was up to 84.9% and 71.1% in 7- and 15-day-old cultures, respectively. Since the inhibition of Af-9 growth by metabolites of was not necessarily associated with inhibition of AfB production and vice versa, we investigated the mechanism of reduction of AfB content at the molecular level by examining two strains: one (T60) that reduced both growth and mycotoxin content; and the other (T44) that reduced mycotoxin content but not Af-9 growth. The expression analyses for the two regulatory genes and , and the structural genes , , and of the aflatoxin biosynthesis cluster indicated that neither strain was able to downregulate the aflatoxin synthesis, leading to the conclusion that the AfB content reduction by these strains was based on other mechanisms, such as enzyme degradation or complexation. Although further studies are envisaged to identify the metabolites involved in the biocontrol of and prevention of aflatoxin accumulation, as well as for assessment of the efficacy under controlled and field conditions, spp. qualify as promising agents and possible alternative options to other biocontrol agents already in use.
Topics: Aflatoxins; Aspergillus flavus; Biological Control Agents; Trichoderma
PubMed: 35202114
DOI: 10.3390/toxins14020086 -
BMJ Paediatrics Open Apr 2023Aflatoxin B1 (AFB1) is a carcinogen produced by and which grow on maize. Given the high prevalence of child stunting (ie, impaired growth) and other nutritional...
Assessment of aflatoxin exposure, growth faltering and the gut microbiome among children in rural Guatemala: protocol for an observational prospective cohort and bioreactor simulations.
INTRODUCTION
Aflatoxin B1 (AFB1) is a carcinogen produced by and which grow on maize. Given the high prevalence of child stunting (ie, impaired growth) and other nutritional disorders in low-income and middle-income countries, where maize is consumed, the role of aflatoxin exposure may be significant. Observational reports have demonstrated associations between aflatoxin exposure and impaired child growth; however, most have been cross-sectional and have not assessed seasonal variations in aflatoxin, food preparation and dynamic changes in growth. Biological mechanistic data on how aflatoxin may exert an impact on child growth is missing. This study incorporates a prospective cohort of children from rural Guatemala to assess (1) temporal associations between aflatoxin exposure and child growth and (2) possible mediation of the gut microbiome among aflatoxin exposure, inflammation and child growth.
METHODS AND ANALYSIS
We will prospectively evaluate aflatoxin exposure and height-for-age difference trajectories for 18 months in a cohort of 185 children aged 6-9 months at enrolment. We will assess aflatoxin exposure levels and biomarkers of gut and systemic inflammation. We will examine the faecal microbiome of each child and identify key species and metabolic pathways for differing AFB1 exposure levels and child growth trajectories. In parallel, we will use bioreactors, inoculated with faeces, to investigate the response of the gut microbiome to varying levels of AFB1 exposure. We will monitor key microbial metabolites and AFB1 biotransformation products to study nutrient metabolism and the impact of the gut microbiome on aflatoxin detoxification/metabolism. Finally, we will use path analysis to summarise the effect of aflatoxin exposure and the gut microbiome on child growth.
ETHICS AND DISSEMINATION
Ethics approval was obtained from Arizona State University Institutional Review Board (IRB; STUDY00016799) and Wuqu' Kawoq/Maya Health Alliance IRB (WK-2022-003). Findings will be disseminated in scientific presentations and peer-reviewed publications.
Topics: Child; Humans; Aflatoxin B1; Aflatoxins; Bioreactors; Cross-Sectional Studies; Gastrointestinal Microbiome; Guatemala; Inflammation; Prospective Studies; Zea mays; Observational Studies as Topic
PubMed: 37080609
DOI: 10.1136/bmjpo-2023-001960 -
Toxins Nov 2021poses a threat to society economy and public health due to aflatoxin production. is a gene located in the aflatoxin gene cluster, but the function of AflN is undefined...
poses a threat to society economy and public health due to aflatoxin production. is a gene located in the aflatoxin gene cluster, but the function of AflN is undefined in . In this study, is knocked out and overexpressed to study the function of AflN. The results indicated that the loss of AflN leads to the defect of aflatoxin biosynthesis. AflN is also found to play a role in conidiation but not hyphal growth and sclerotia development. Moreover, AlfN is related to the response to environmental oxidative stress and intracellular levels of reactive oxygen species. At last, AflN is involved in the pathogenicity of to host. These results suggested that AflN played important roles in aflatoxin biosynthesis, conidiation and reactive oxygen species generation in , which will be helpful for the understanding of function, and will be beneficial to the prevention and control of and aflatoxins contamination.
Topics: Aflatoxins; Aspergillus flavus; Fungal Proteins; Gene Expression Regulation, Fungal; Multigene Family; Oxidative Stress; Reactive Oxygen Species
PubMed: 34822615
DOI: 10.3390/toxins13110831 -
Archives of Toxicology Dec 2023Aflatoxin B (AFB) is a highly hepatotoxic and carcinogenic mycotoxin produced by Aspergillus species. The compound is mainly metabolized in the liver and its metabolism...
Aflatoxin B (AFB) is a highly hepatotoxic and carcinogenic mycotoxin produced by Aspergillus species. The compound is mainly metabolized in the liver and its metabolism varies between species. The present study quantified relevant AFB- metabolites formed by mouse, rat, and human primary hepatocytes after treatment with 1 µM and 10 µM AFB. The use of liquid chromatographic separation coupled with tandem mass spectrometric detection enabled the selective and sensitive determination of phase I and phase II metabolites of AFB over incubation times of up to 24 h. The binding of AFB to macromolecules was also considered. The fastest metabolism of AFB was observed in mouse hepatocytes which formed aflatoxin P as a major metabolite and also its glucuronidated form, while AFP occurred only in traces in the other species. Aflatoxin M was formed in all species and was, together with aflatoxin Q and aflatoxicol, the main metabolite in human cells. Effective epoxidation led to high amounts of DNA adducts already 30 min post-treatment, especially in rat hepatocytes. Lower levels of DNA adducts and fast DNA repair were found in mouse hepatocytes. Also, protein adducts arising from reactive intermediates were formed rapidly in all three species. Detoxification via glutathione conjugation and subsequent formation of the N-acetylcysteine derivative appeared to be similar in mice and in rats and strongly differed from human hepatocytes which did not form these metabolites at all. The use of qualitative reference material of a multitude of metabolites and the comparison of hepatocyte metabolism in three species using advanced methods enabled considerations on toxification and detoxification mechanisms of AFB. In addition to glutathione conjugation, phase I metabolism is strongly involved in the detoxification of AFB.
Topics: Humans; Rats; Mice; Animals; Aflatoxin B1; Chromatography, High Pressure Liquid; DNA Adducts; Tandem Mass Spectrometry; DNA; Aflatoxins; Liver; Hepatocytes; Glutathione
PubMed: 37794256
DOI: 10.1007/s00204-023-03607-z -
Journal of Food Protection Jan 2020Texas A&M AgriLife Research (hereafter AgriLife) introduced a quality systems approach to accurately measure and manage aflatoxin that resulted in improved food safety...
Texas A&M AgriLife Research (hereafter AgriLife) introduced a quality systems approach to accurately measure and manage aflatoxin that resulted in improved food safety for approximately 10 million Kenyans. A quality systems approach contains elements that ensure laboratory testing competence. In this study, quality system elements included analyst training and qualification, proficiency testing, use of reference material to support analytical traceability and define analytical uncertainty, development and implementation of a food safety plan by commercial maize () millers, and verification of testing accuracy at the AgriLife laboratory accredited by the Kenya Accreditation Service under the International Organization for Standardization/International Electrotechnical Commission 17025:2005 standard. In 2014 and 2015, five proficiency rounds were performed, ranging in aflatoxin concentrations of 5 to 40 μg/kg. Five laboratories had a -score of >3, and all of these were for the fifth proficiency round with an aflatoxin content of 5 μg/kg. In 2015, 31 analysts qualified to participate in the program at 15 maize mills. The analysts' qualification for seven test samples, which ranged from 3.1 to 28 μg/kg total aflatoxin, resulted in an average relative standard deviation of 19.2% across all participants and test methods. Independent testing of participating mill verification results before and after analyst implementation of the quality systems approach revealed an improvement in measure accuracy.
Topics: Accreditation; Aflatoxins; Food Safety; Kenya; Laboratories
PubMed: 31855611
DOI: 10.4315/0362-028X.JFP-19-292 -
Plant Disease Sep 2021Aflatoxins are potent mycotoxins that contaminate food and feed, thereby impacting health and trade. Biopesticides with atoxigenic isolates as active ingredients are...
Aflatoxins are potent mycotoxins that contaminate food and feed, thereby impacting health and trade. Biopesticides with atoxigenic isolates as active ingredients are used to reduce aflatoxin contamination in crops. The mechanism of aflatoxin biocontrol is primarily attributed to competitive exclusion but, sometimes, aflatoxin is reduced by greater amounts than can be explained by displacement of aflatoxin-producing fungi on the crop. Objectives of this study were to (i) evaluate the ability of atoxigenic genotypes to degrade aflatoxin B (AFB1) and (ii) characterize impacts of temperature, time, and nutrient availability on AFB1 degradation by atoxigenic . Aflatoxin-contaminated maize was inoculated with atoxigenic isolates in three separate experiments that included different atoxigenic genotypes, temperature, and time as variables. Atoxigenic genotypes varied in aflatoxin degradation but all degraded AFB1 >44% after 7 days at 30°C. The optimum temperature for AFB1 degradation was 25 to 30°C, which is similar to the optimum range for AFB1 production. In a time-course experiment, atoxigenics degraded 40% of AFB1 within 3 days, and 80% of aflatoxin was degraded by day 21. Atoxigenic isolates were able to degrade and utilize AFB1 as a sole carbon source in a chemically defined medium but quantities of AFB1 degraded declined as glucose concentrations increased. Degradation may be an additional mechanism through which atoxigenic biocontrol products reduce aflatoxin contamination pre- or postharvest. Thus, selection of optimal atoxigenic active ingredients can include assessment of both competitive ability in agricultural fields and their ability to degrade aflatoxins.
Topics: Aflatoxin B1; Aflatoxins; Aspergillus flavus; Biological Control Agents; Zea mays
PubMed: 33754847
DOI: 10.1094/PDIS-01-21-0066-RE -
BMC Microbiology Aug 2021Aspergillus species cause aflatoxin contamination in groundnut kernels, being a health threat in agricultural products and leading to commodity rejection by domestic and...
BACKGROUND
Aspergillus species cause aflatoxin contamination in groundnut kernels, being a health threat in agricultural products and leading to commodity rejection by domestic and international markets. Presence of Aspergillus flavus and A. parasiticus colonizing groundnut in eastern Ethiopia, as well as presence of aflatoxins have been reported, though in this region, no genetic studies have been done of these species in relation to their aflatoxin production.
RESULTS
In this study, 145 Aspergillus isolates obtained from groundnut kernels in eastern Ethiopia were genetically fingerprinted using 23 Insertion/Deletion (InDel) markers within the aflatoxin-biosynthesis gene cluster (ABC), identifying 133 ABC genotypes. Eighty-four isolates were analyzed by Ultra-Performance Liquid Chromatography (UPLC) for in vitro aflatoxin production. Analysis of genetic distances based on the approximately 85 kb-ABC by Neighbor Joining (NJ), 3D-Principal Coordinate Analysis (3D-PCoA), and Structure software, clustered the isolates into three main groups as a gradient in their aflatoxin production. Group I, contained 98% A. flavus, including L- and non-producers of sclerotia (NPS), producers of B and B aflatoxins, and most of them collected from the lowland-dry Babile area. Group II was a genetic admixture population of A. flavus (NPS) and A. flavus S morphotype, both low producers of aflatoxins. Group III was primarily represented by A. parasiticus and A. flavus S morphotype isolates both producers of B, B and G, G aflatoxins, and originated from the regions of Darolabu and Gursum. The highest in vitro producer of aflatoxin B was A. flavus NPS N1436 (77.98 μg/mL), and the highest producer of aflatoxin G was A. parasiticus N1348 (50.33 μg/mL), these isolates were from Gursum and Darolabu, respectively.
CONCLUSIONS
To the best of our knowledge, this is the first study that combined the use of InDel fingerprinting of the ABC and corresponding aflatoxin production capability to describe the genetic diversity of Aspergillus isolates from groundnut in eastern Ethiopia. Three InDel markers, AFLC04, AFLC08 and AFLC19, accounted for the main assignment of individuals to the three Groups; their loci corresponded to aflC (pksA), hypC, and aflW (moxY) genes, respectively. Despite InDels within the ABC being often associated to loss of aflatoxin production, the vast InDel polymorphism observed in the Aspergillus isolates did not completely impaired their aflatoxin production in vitro.
Topics: Aflatoxins; Agriculture; Arachis; Aspergillus flavus; DNA Fingerprinting; Ethiopia; Food Contamination; Multigene Family
PubMed: 34454439
DOI: 10.1186/s12866-021-02290-3 -
Toxicological Sciences : An Official... Mar 2011Since their discovery 50 years ago, the aflatoxins have become recognized as ubiquitous contaminants of the human food supply throughout the economically developing... (Review)
Review
Since their discovery 50 years ago, the aflatoxins have become recognized as ubiquitous contaminants of the human food supply throughout the economically developing world. The adverse toxicological consequences of these compounds in populations are quite varied because of a wide range of exposures leading to acute effects, including rapid death, and chronic outcomes such as hepatocellular carcinoma. Furthermore, emerging studies describe a variety of general adverse health effects associated with aflatoxin, such as impaired growth in children. Aflatoxin exposures have also been demonstrated to multiplicatively increase the risk of liver cancer in people chronically infected with hepatitis B virus (HBV) illustrating the deleterious impact that even low toxin levels in the diet can pose for human health. The public health impact of aflatoxin exposure is pervasive. Aflatoxin biomarkers of internal and biologically effective doses have been integral to the establishment of the etiologic role of this toxin in human disease through better estimates of exposure, expanded knowledge of the mechanisms of disease pathogenesis, and as tools for implementing and evaluating preventive interventions.
Topics: Aflatoxins; Animals; Environmental Exposure; Food Contamination; History, 20th Century; History, 21st Century; Humans; Poisons; Public Health; Toxicology; Translational Research, Biomedical
PubMed: 20881231
DOI: 10.1093/toxsci/kfq283 -
Toxins Sep 2021Aflatoxins (AFs) are secondary metabolites that represent serious threats to human and animal health. They are mainly produced by strains of the saprophytic fungus ,... (Review)
Review
Aflatoxins (AFs) are secondary metabolites that represent serious threats to human and animal health. They are mainly produced by strains of the saprophytic fungus , which are abundantly distributed across agricultural commodities. AF contamination is receiving increasing attention by researchers, food producers, and policy makers in China, and several interesting review papers have been published, that mainly focused on occurrences of AFs in agricultural commodities in China. The goal of this review is to provide a wider scale and up-to-date overview of AF occurrences in different agricultural products and of the distribution of across different food and feed categories and in Chinese traditional herbal medicines in China, for the period 2000-2020. We also highlight the health impacts of chronic dietary AF exposure, the recent advances in biological AF mitigation strategies in China, and recent Chinese AF standards.
Topics: Aflatoxins; Aspergillus; China; Crops, Agricultural; Drug Contamination; Drugs, Chinese Herbal; Food Contamination; Humans
PubMed: 34678973
DOI: 10.3390/toxins13100678 -
Toxins Sep 2022Aflatoxin B1 (AFB1), a common contaminant in food and feed during storage, does great harm to human and animal health. Five essential oils (thymol, carvacrol,...
Aflatoxin B1 (AFB1), a common contaminant in food and feed during storage, does great harm to human and animal health. Five essential oils (thymol, carvacrol, cinnamaldehyde, eugenol, and citral) were tested for their inhibition effect against Aspergillus flavus (A. flavus) in broth and feed. Cinnamaldehyde and citral were proven to be most effective against A. flavus compared to others and have a synergistic effect when used simultaneously. The broth supplemented with cinnamaldehyde and citral was inoculated with A. flavus (106 CFU/mL) by using the checkerboard method, and mold counts and AFB1 production were tested on days 0, 1, 3, and 5. Similarly, 100 g poultry feed supplemented with the mixture of cinnamaldehyde and citral at the ratio 1:1 was also inoculated with A. flavus, and the same parameters were tested on days 0, 7, 14, and 21. In poultry feed, cinnamaldehyde and citral significantly reduced mold counts and AFB1 concentrations (p < 0.05). Results showed that cinnamaldehyde and citral have a positive synergy effect and could both inhibit at least 90% the fungal growth and aflatoxin B1 production at 40 μg/mL in broth and poultry feed, and could be an alternative to control aflatoxin contamination in food and feed in future.
Topics: Animals; Humans; Aspergillus flavus; Aflatoxin B1; Oils, Volatile; Eugenol; Thymol; Poultry; Aflatoxins
PubMed: 36287924
DOI: 10.3390/toxins14100655