-
Microbiology Spectrum Feb 2022Aspergillus flavus , a gene encoding a Zn(II)Cys DNA-binding domain, is an important transcriptional regulator of the aflatoxin biosynthesis gene cluster. Our previous...
Aspergillus flavus , a gene encoding a Zn(II)Cys DNA-binding domain, is an important transcriptional regulator of the aflatoxin biosynthesis gene cluster. Our previous results of Gene ontology (GO) analysis for the binding sites of AflR in A. flavus suggest that AflR may play an integrative regulatory role. In this study the Δ and overexpression (OE) strains based on the well-established double-crossover recombinational technique were constructed to investigate the integrative function of the gene in A. flavus. The disruption of severely affected the aflatoxin biosynthetic pathway, resulting in a significant decrease in aflatoxin production. The aflatoxin B (AFB) of the Δ strain was 180 ng/mL and aflatoxin B (AFB) was 2.95 ng/mL on YES medium for 5 days, which was 1/1,000 of that produced by the wild-type strain (WT). In addition, the Δ strain produced relatively sparse conidia and a very small number of sclerotia. On the seventh day, the sclerotia yield on each plate of the WT and OE strains exceeded 1,000, while the sclerotial formation of the Δ strain was not detected until 14 days. However, the biosynthesis of cyclopiazonic acid (CPA) was not affected by gene disruption. Transcriptomic analysis of the Δ strain grown on potato dextrose agar (PDA) plates at 0 h, 24 h, and 72 h showed that expression of clustering genes involved in the biosynthesis of aflatoxin was significantly downregulated. Meanwhile, the Δ strain compared with the WT strain showed significant expression differences in genes involved in spore germination, sclerotial development, and carbohydrate metabolism compared to the WT. The results demonstrated that the A. flavus gene also played a positive role in the fungal growth and development in addition to aflatoxin biosynthesis. Past studies of the A. flavus gene and its orthologues in related Aspergillus species were solely focused on their roles in secondary metabolism. In this study, we used the Δ and OE strains to demonstrate the role of in growth and development of A. flavus. For the first time, we confirmed that the Δ strain also was defective in production of conidia and sclerotia, asexual propagules of A. flavus. Our transcriptomic analysis further showed that genes involved in spore germination, sclerotial development, aflatoxin biosynssssthesis, and carbohydrate metabolism exhibited significant differences in the Δ strain compared with the WT strain. Our study indicates that AflR not only plays an important role in regulating aflatoxin synthesis but also in playing a positive role in the conidial formation and sclerotial development in A. flavus. This study reveals the critical and positive role of the gene in fungal growth and development, and provides a theoretical basis for the genetic studies of other .
Topics: Aflatoxins; Aspergillus flavus; Fungal Proteins; Gene Expression Profiling; Gene Expression Regulation, Fungal; Multigene Family; Phylogeny; Spores, Fungal; Transcription, Genetic
PubMed: 35080432
DOI: 10.1128/spectrum.00791-21 -
Toxins Mar 2021Aflatoxins (AFs) are among the most harmful fungal secondary metabolites imposing serious health risks on both household animals and humans. The more frequent occurrence... (Review)
Review
Aflatoxins (AFs) are among the most harmful fungal secondary metabolites imposing serious health risks on both household animals and humans. The more frequent occurrence of aflatoxins in the feed and food chain is clearly foreseeable as a consequence of the extreme weather conditions recorded most recently worldwide. Furthermore, production parameters, such as unadjusted variety use and improper cultural practices, can also increase the incidence of contamination. In current aflatoxin control measures, emphasis is put on prevention including a plethora of pre-harvest methods, introduced to control infestations and to avoid the deleterious effects of aflatoxins on public health. Nevertheless, the continuous evaluation and improvement of post-harvest methods to combat these hazardous secondary metabolites are also required. Already in-use and emerging physical methods, such as pulsed electric fields and other nonthermal treatments as well as interventions with chemical agents such as acids, enzymes, gases, and absorbents in animal husbandry have been demonstrated as effective in reducing mycotoxins in feed and food. Although most of them have no disadvantageous effect either on nutritional properties or food safety, further research is needed to ensure the expected efficacy. Nevertheless, we can envisage the rapid spread of these easy-to-use, cost-effective, and safe post-harvest tools during storage and food processing.
Topics: Aflatoxins; Animal Feed; Animals; Aspergillus; Crop Protection; Crops, Agricultural; Food Chain; Food Contamination; Food Handling; Food Microbiology; Humans; Risk Assessment; Secondary Metabolism
PubMed: 33808964
DOI: 10.3390/toxins13030204 -
BioMed Research International 2022. Poultry feed contamination due to mycotoxins is one of the major threats to the growing poultry industry. Surveillance of different mycotoxins, including aflatoxin, is...
. Poultry feed contamination due to mycotoxins is one of the major threats to the growing poultry industry. Surveillance of different mycotoxins, including aflatoxin, is very important to control economic and health hazards associated with these toxins. Studies reporting aflatoxin levels in poultry feed are limited. Therefore, this study was conducted to examine the occurrence of total aflatoxin in poultry feed. This study is the first-ever documentation about the frequency and quantitative estimations of total aflatoxin levels in poultry feed consumed to provide solid feedback to the poultry industrialists and researchers involved in studying the mycotoxins. . Contamination of poultry feed with mycotoxins such as aflatoxin is a major concern for the poultry industry that results in a significant economic loss and directly affects consumers. Monitoring the aflatoxin levels in poultry feed is crucial for controlling economic loss and decreasing the health hazards to the population. This study was conducted to examine the occurrence of total aflatoxin in poultry feed in a high consumption area. Three different poultry feeds, i.e., starter, grower, and finisher, were assessed through continuous sampling from farms. The incidence of positive samples for aflatoxin contamination was 92.5%. Grower feed had the highest frequency (100%) of aflatoxin positive samples and aflatoxin levels with a mean value of 56.34 ppb. Further, the range of moisture content was around 6.8%-10.98%. No significant correlation between humidity and aflatoxin contamination was revealed when analyzed by Pearson's correlation coefficient with of 0.05 and value of 0.13. The results warrant the need for constant monitoring programs for the prevention of aflatoxin contamination in local poultry farms.
Topics: Aflatoxins; Animal Feed; Animals; Food Contamination; Pakistan; Poultry
PubMed: 35141333
DOI: 10.1155/2022/5397561 -
International Journal of Environmental... Oct 2020Crops contaminated by aflatoxins (AFs), the toxic and carcinogenic mycotoxins produced namely by and , have severe impacts on human health. Changes in temperature and... (Review)
Review
Crops contaminated by aflatoxins (AFs), the toxic and carcinogenic mycotoxins produced namely by and , have severe impacts on human health. Changes in temperature and water availability related to actual climate changes (increased temperature, heavy rainfalls, and droughts) are modulating factors of mould growth and production of mycotoxins. To protect human and animal health from the harmful effects caused by AFs, the development of a safe and effective multifaceted approach in combating food and feed contamination with AFs is necessary. This review aims to collect and analyze the available information regarding AF presence in food and feed to reinforce AF management and to prevent health issues related to the AF exposure in the light of actual climate changes.
Topics: Aflatoxins; Animals; Aspergillus; Aspergillus flavus; Climate Change; Food Contamination; Fungi; Humans
PubMed: 33120863
DOI: 10.3390/ijerph17217850 -
Toxins Feb 2023Aflatoxin B (AFB) exhibits the most potent mutagenic and carcinogenic activity among aflatoxins. For this reason, AFB is recognized as a human group 1 carcinogen by the... (Review)
Review
Aflatoxin B (AFB) exhibits the most potent mutagenic and carcinogenic activity among aflatoxins. For this reason, AFB is recognized as a human group 1 carcinogen by the International Agency of Research on Cancer. Consequently, it is essential to determine its properties and behavior in different chemical systems. The chemical properties of AFB can be explored using computational chemistry, which has been employed complementarily to experimental investigations. The present review includes in silico studies (semiempirical, Hartree-Fock, DFT, molecular docking, and molecular dynamics) conducted from the first computational study in 1974 to the present (2022). This work was performed, considering the following groups: (a) molecular properties of AFB (structural, energy, solvent effects, ground and the excited state, atomic charges, among others); (b) theoretical investigations of AFB (degradation, quantification, reactivity, among others); (c) molecular interactions with inorganic compounds (Ag, Zn, and Mg); (d) molecular interactions with environmentally compounds (clays); and (e) molecular interactions with biological compounds (DNA, enzymes, cyclodextrins, glucans, among others). Accordingly, in this work, we provide to the stakeholder the knowledge of toxicity of types of AFB-derivatives, the structure-activity relationships manifested by the bonds between AFB and DNA or proteins, and the types of strategies that have been employed to quantify, detect, and eliminate the AFB molecule.
Topics: Humans; Aflatoxin B1; Molecular Docking Simulation; Aflatoxins; Structure-Activity Relationship; Carcinogens; DNA
PubMed: 36828449
DOI: 10.3390/toxins15020135 -
Toxins Apr 2022Contamination of food chains by toxigenic fungi and aflatoxins is a global problem that causes damage to human health, as well as to crop and livestock production. The...
Contamination of food chains by toxigenic fungi and aflatoxins is a global problem that causes damage to human health, as well as to crop and livestock production. The objective is to evaluate and total aflatoxins (AFs) occurrence in totally mixed rations (TMRs) for dairy cows and aflatoxin M (AFM) in milk for human consumption. Ninety-nine dairy production units located in Aguascalientes, Mexico, were randomly selected, and samples were collected from TMRs, raw milk, and milk marketed in the city in two consecutive agricultural cycles. AFs were quantified in TMRs and milk by indirect enzyme immunoassay and HPLC; aflatoxigenic and molecular (PCR) capacity of monosporic isolates in the feed was characterized. All feed, raw, and pasteurized milk samples showed aflatoxin contamination (26.0 ± 0.4 µg/kg, 32.0 ± 1.0, and 31.3 ± 0.7 ng/L, respectively), and a significant proportion (90.4, 11.3, and 10.3%) exceeded the locally applied maximum permissible limits for feed and milk (20.0 µg/kg and 50 ng/L). Aflatoxin contamination in both TMRs and milk indicated a seasonal influence, with a higher concentration in the autumn-winter cycle when conditions of higher humidity prevail. The results obtained suggest the existence of contamination by aflatoxigenic and aflatoxins in the diet formulated for feeding dairy cows and, consequently, in the dairy food chain of this region of the Mexican Highland Plateau.
Topics: Aflatoxin M1; Aflatoxins; Animals; Aspergillus flavus; Cattle; Female; Mexico; Milk
PubMed: 35622539
DOI: 10.3390/toxins14050292 -
Toxins Mar 2023Aflatoxin B1 (AFB1), ochratoxin A (OTA), and deoxynivalenol (DON) are the three mycotoxins that have received the most scholarly attention and have been tested most... (Review)
Review
Aflatoxin B1 (AFB1), ochratoxin A (OTA), and deoxynivalenol (DON) are the three mycotoxins that have received the most scholarly attention and have been tested most routinely in clinics. These mycotoxins not only suppress immune responses but also induce inflammation and even increase susceptibility to pathogens. Here, we comprehensively reviewed the determining factors for the bidirectional immunotoxicity of the three mycotoxins, their effects on pathogens, and their action mechanisms. The determining factors include mycotoxin exposure doses and times, as well as species, sex, and some immunologic stimulants. Moreover, mycotoxin exposure can affect the infection severity of some pathogens, including bacteria, viruses, and parasites. Their specific action mechanisms include three aspects: (1) mycotoxin exposure directly promotes the proliferation of pathogenic microorganisms; (2) mycotoxins produce toxicity, destroy the integrity of the mucosal barrier, and promote inflammatory response, thereby improving the susceptibility of the host; (3) mycotoxins reduce the activity of some specific immune cells and induce immune suppression, resulting in reduced host resistance. The present review will provide a scientific basis for the control of these three mycotoxins and also provide a reference for research on the causes of increased subclinical infections.
Topics: Mycotoxins; Bacteria; Aflatoxin B1
PubMed: 36977078
DOI: 10.3390/toxins15030187 -
Toxins Sep 2023In this study, aflatoxins (AFs) and ochratoxin A (OTA) were analyzed in grains, specifically wheat and corn, from Albania. To summarize, 71 wheat and 45 corn samples...
In this study, aflatoxins (AFs) and ochratoxin A (OTA) were analyzed in grains, specifically wheat and corn, from Albania. To summarize, 71 wheat and 45 corn samples from different growing areas were collected. The multi-toxin analytical procedure involved sample extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The incidence of AF was 18% in the analyzed wheat and 71% in the corn samples. The concentration of AFs was much higher in the corn samples than in the wheat samples. The maximum permitted levels for aflatoxin B1 (AFB1) and total AFs were not exceeded in the wheat samples, while they were exceeded in 36% of the corn samples. In the wheat samples, the AFB1 concentration varied between 0.2 and 0.4 µg kg. However, the highest concentrations in the corn samples were 2057, 2944, and 3550 µg kg. OTA was present in only three corn samples and one wheat sample. However, all contaminated samples exceeded the maximum permitted levels. This report reveals the presence of AFs and OTA in grain commodities, specifically wheat and corn, grown in Albania.
Topics: Aflatoxins; Zea mays; Triticum; Chromatography, Liquid; Albania; Incidence; Food Contamination; Tandem Mass Spectrometry; Ochratoxins; Aflatoxin B1; Chromatography, High Pressure Liquid
PubMed: 37755993
DOI: 10.3390/toxins15090567 -
International Journal of Environmental... Sep 2019Among the array of structurally and toxicologically diverse mycotoxins, aflatoxins have attracted the most interest of scientific research due to their high toxicity and...
Among the array of structurally and toxicologically diverse mycotoxins, aflatoxins have attracted the most interest of scientific research due to their high toxicity and incidence in foods and feeds. Despite the undeniable progress made in various aspects related to aflatoxins, the ultimate goal consisting of reducing the associated public health risks worldwide is far from being reached due to multiplicity of social, political, economic, geographic, climatic, and development factors. However, a reasonable degree of health protection is attained in industrialized countries owing to their scientific, administrative, and financial capacities allowing them to use high-tech agricultural management systems. Less fortunate situations exist in equatorial and sub-equatorial developing countries mainly practicing traditional agriculture managed by smallholders for subsistence, and where the climate is suitable for mould growth and aflatoxin production. This situation worsens due to climatic change producing conditions increasingly suitable for aflatoxigenic mould growth and toxin production. Accordingly, it is difficult to harmonize the regulatory standards of aflatoxins worldwide, which prevents agri-foods of developing countries from accessing the markets of industrialized countries. To tackle the multi-faceted aflatoxin problem, actions should be taken collectively by the international community involving scientific research, technological and social development, environment protection, awareness promotion, etc. International cooperation should foster technology transfer and exchange of pertinent technical information. This review presents the main historical discoveries leading to our present knowledge on aflatoxins and the challenges that should be addressed presently and in the future at various levels to ensure higher health protection for everybody. In short, it aims to elucidate where we come from and where we should go in terms of aflatoxin research/development.
Topics: Aflatoxins; Agriculture; Biomedical Research; Climate Change; Developing Countries; Food Microbiology; Global Health; Health Policy; History, 17th Century; History, 19th Century; History, 20th Century; History, Ancient; Humans; Mycotoxicosis; Poisons; Prospective Studies; Public Health; Retrospective Studies
PubMed: 31569703
DOI: 10.3390/ijerph16193633 -
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