Occurrence, dietary exposure and risk assessment of aflatoxins in arepa, bread and rice

Impact of Kluyveromyces marxianus VM004 culture conditions on the cell wall structure and its influence on aflatoxin B1 binding

The aim of this study was to determine the impact of Kluyveromyces marxianus VM004 culture conditions on the cell wall (CW) structure and its influence on aflatoxin B1 binding. The yeast was inoculated into two types of culture media: yeast extract-peptone-dextrose (YPD) broth and dried distiller's grains with solubles (DDG). The CW was extracted from the biomass produced in these media. AFB1 (150ng/ml) adsorption tests using the biomass (1×107cells/ml) and the CW (0.001g) were performed at pH 2 and pH 8. Transmission electron microscopy (TEM) evaluated the CW thickness, and infrared spectroscopy (IR) determined the CW composition. Biomass production in YPD was higher than that in DDG. Cell diameter (μm) and CW thickness (μm) increased in the DDG medium. The CW percentage obtained in DDG was higher than that in YPD. The absorbance of carbohydrates by IR was higher in YPD. pH influenced AFB1 adsorption, which was lower at pH 8. The proportion of β-glucan and chitin present in CW was higher in the YPD medium. The IR method allowed to study the CW carbohydrate variation under the influence of these carbon sources. In conclusion, the culture media composition influenced the β-glucan and chitin composition and consequently, AFB1 adsorption.

Curcumin: A Potential Detoxifier Against Chemical and Natural Toxicants

The human body gets exposed to a variety of toxins intentionally or unintentionally on a regular basis from sources such as air, water, food, and soil. Certain toxins can be synthetic, while some are biological. The toxins affect the various parts of the body by activating numerous pro-inflammatory markers, like oxidative stresses, that tend to disturb the normal function of the organs ultimately. Nowadays, people use different types of herbal treatments, viz., herbal drinks that contain different spices for detoxification of their bodies. One such example is turmeric, the most commonly available spice in the kitchen and used across all kinds of households. Turmeric contains curcumin, which is a natural polyphenol. Curcumin is a medicinal compound with different biological activities, such as antioxidant, antineoplastic, anti-inflammatory, and antibacterial. Hence, this review gives a comprehensive insight into the promising potential of curcumin in the detoxification of heavy metals, carbon tetrachloride, drugs, alcohol, acrylamide, mycotoxins, nicotine, and plastics. The review encompasses diverse animal-based studies portraying curcumin's role in nullifying the different toxic effects in various organs of the body (especially the liver, kidney, testicles, and brain) by enhancing defensive signaling pathways, improving antioxidant enzyme levels, inhibiting pro-inflammatory markers activities and so on. Furthermore, this review also argues over curcumin's safety assessment for its utilization as a detoxifying agent.

The concentration of malachite green in fish: a systematic review, meta-analysis, and probabilistic risk assessment

Malachite Green (MG) is an antibiotic with antifungal activity, which is illegal to use in agriculture due to its mutagenic and teratogenic properties. Several scientific papers have been published on MG in fish. Therefore, an attempt was made to determine the meta-analysis concentration of MG in fish based on countries and types of fish subgroups, as well as the health risks of consumers, using the Monte Carlo simulation (MCS) model. The three countries with the highest concentration of MG were Iran (14.697 µg/kg), Brazil (2.840 µg/kg), and China (2.277 µg/kg). The overall pooled concentration of MG in fish was 3.036 µg/kg, 95%CI (2.860-3.212 µg/kg), and the highest concentration of MG was observed in Pacu fish (6.603 µg/kg). The health risk assessment shows adults in Malaysia, China, and Iran and children in Italy, Spain, Brazil, Malaysia, China, and Iran are at considerable risk (MOE <10,000); hence, carrying out control plans in these countries is recommended.

Reduction in mycotoxin levels of African nutmeg (Monodora myristica) powder using a high-energy electron beam

This study investigated the role of irradiation with a high-energy electron beam in reducing mycotoxin levels of African nutmeg powder (ANP) samples. African nutmeg was procured from a local market in Accra, Ghana, cleaned, milled, packaged and irradiated using electrons of energy 9 MeV at doses of 2, 4, 6 and 8 kGy. Un-irradiated ANP served as a control. Mycotoxin levels of the treated samples were determined using appropriate standard methods. Aflatoxins B1 (AFB1) and B2 (AFB2) as well as ochratoxin A (OTA) were detected in the nutmeg samples. Irradiation significantly (p < 0.05) reduced mycotoxin levels of the ANP with increasing doses. Aflatoxins G1 and G2 were not detected in any of the samples. A dose of 8 kGy was effective in reducing the mycotoxin levels below the permissible limit in food. This suggests that a high-energy electron beam is effective in reducing mycotoxin levels in African nutmeg powder.

Aflatoxins in the rice production chain: A review on prevalence, detection, and decontamination strategies

Rice (Oryza sativa L.) is one of the most consumed cereals that along with several important nutritional constituents typically provide more than 21% of the caloric requirements of human beings. Aflatoxins (AFs) are toxic secondary metabolites of several Aspergillus species that are prevalent in cereals, including rice. This review provides a comprehensive overview on production factors, prevalence, regulations, detection methods, and decontamination strategies for AFs in the rice production chain. The prevalence of AFs in rice is more prominent in African and Asian than in European countries. Developed nations have more stringent regulations for AFs in rice than in the developing world. The contamination level of AFs in the rice varied at different stages of rice production chain and is affected by production practices, environmental conditions comprising temperature, humidity, moisture, and water activity as well as milling operations such as de-husking, parboiling, and polishing. A range of methods including chromatographic techniques, immunochemical methods, and spectrophotometric methods have been developed, and used for monitoring AFs in rice. Chromatographic methods are the most used methods of AFs detection followed by immunochemical techniques. AFs decontamination strategies adopted worldwide involve various physical, chemical, and biological strategies, and even using plant materials. In conclusion, adopting good agricultural practices, implementing efficient AFs detection methods, and developing innovative aflatoxin decontamination strategies are imperative to ensure the safety and quality of rice for consumers.

Antimicrobial Activity of Hydrogen Peroxide for Application in Food Safety and COVID-19 Mitigation: An Updated Review

Hydrogen peroxide (H2O2) is a well-known agent with a broad-spectrum antimicrobial activity against pathogenic bacteria, fungi, and viruses. It is a colorless liquid and commercially available in aqueous solution over a wide concentration range. It has been extensively used in the food industry by virtue of its strong oxidizing property and its ability to cause cellular oxidative damage in microbial cells. This review comprehensively documents recent research on the antimicrobial activity of H2O2 against organisms of concern for the food industry, as well as its effect against SARS-CoV-2 responsible for the COVID-19 pandemic. In addition, factors affecting the antimicrobial effectiveness of H2O2, different applications of H2O2 as a sanitizer or disinfectant in the food industry as well as safety concerns associated with H2O2 are discussed. Finally, recent efforts in enhancing the antimicrobial efficacy of H2O2 are also outlined.

Human health risk assessment based on a total diet study of daily mercury intake in Chengdu, China

To assess the total daily mercury intake and main exposure sources of residents, six food groups, including marine fish, freshwater fish, poultry, livestock, vegetables, and cereals, were collected from five districts of Chengdu, China. The median concentrations of total mercury (THg) and methylmercury (MeHg) were 12.8 and 6.94 μg kg-1 ww, respectively. Cereals (32.2%), vegetables (30.5%), and livestock (16.2%) contributed to a much larger extent to the total consumption for the participants in Chengdu. All food categories that contributed the most of THg (2.16 μg day-1) and MeHg 1.44 (μg day-1) to the daily intake in Chengdu were cereals and marine fish, respectively. The total Hazard Ratios values below 1 in this study indicate that there is no health risk associated with Hg ingestion from the consumption of these foods for the residents in Chengdu.

Review of the Terminology, Approaches, and Formulations Used in the Guidelines on Quantitative Risk Assessment of Chemical Hazards in Food

This paper reviews the published terminology, mathematical models, and the possible approaches used to characterise the risk of foodborne chemical hazards, particularly pesticides, metals, mycotoxins, acrylamide, and polycyclic aromatic hydrocarbons (PAHs). The results confirmed the wide variability of the nomenclature used, e.g., 28 different ways of referencing exposure, 13 of cancer risk, or 9 of slope factor. On the other hand, a total of 16 equations were identified to formulate all the risk characterisation parameters of interest. Therefore, the present study proposes a terminology and formulation for some risk characterisation parameters based on the guidelines of international organisations and the literature review. The mathematical model used for non-genotoxic hazards is a ratio in all cases. However, the authors used the probability of cancer or different ratios, such as the margin of exposure (MOE) for genotoxic hazards. For each effect studied per hazard, the non-genotoxic effect was mostly studied in pesticides (79.73%), the genotoxic effect was mostly studied in PAHs (71.15%), and both effects were mainly studied in metals (59.4%). The authors of the works reviewed generally opted for a deterministic approach, although most of those who assessed the risk for mycotoxins or the ratio and risk for acrylamide used the probabilistic approach.

Control of aflatoxin biosynthesis by sulfur containing benzimidazole derivatives: In-silico interaction, biological activity, and gene regulation of Aspergillus flavus

Aspergillus flavus producing aflatoxins is one of the potent contaminants of raw food commodities during pre-and post-harvest crops. Aflatoxins are the group of secondary metabolites a subset of natural polyketides. Our major focus is on the inhibition of the biosynthesis pathway of aflatoxin by targeting the enzymes involved. Benzimidazoles are known antimicrobial compounds. In this study the sulfur containing benzimidazole derivatives were tested for their antifungal and antiaflatoxigenic activity. The fungal growth and aflatoxin production was analysed in culture medium as well as in the rice. Inhibition of specific genes was studied in terms of mRNA expression and the interaction of test compound with polyketide synthases by in-silico molecular docking. Substitution at the 6th position of 2-(2-thienyl) benzimidazole (2-TBD) reduced the antifungal property of benzimidazole but effectively inhibited the aflatoxin synthesis in the culture medium as well as in the rice from the toxigenic strain of A. flavus. Among the derivatives tested, the methyl group containing 2-(2-thienyl)- 6-methylbenzimidazole (6-MTBD) inhibited aflatoxin B1 most effectively followed by carboxylic group containing 2-(2-thienyl) benzimidazole-6-carboxylic acid (6-TBCA) with IC50 value of 12.36 and 18.25 µg/mL respectively. Molecular docking study shows that 2-(2-thienyl) benzimidazole-6-carbonitrile (6-CTBD) and 6-MTBD occupy same pocket on TE domain of PksA with similar range of binding energy, however the experimental data show a different effect on the biosynthesis of AFB1. 6-MTBD effectively inhibited the AFB1 synthesis (97%) while 6-CTBD could not (39.5%). Data obtained from the expression study also supports the experimental observations. These compounds are non-toxic to mammalian cells. These benzimidazole derivatives inhibit toxic secondary metabolites without affecting the growth of the fungi hence can be used during fermentation to avoid mycotoxin contamination.

A 10-year analysis of RASFF notifications for mycotoxins in nuts. Trend in key mycotoxins and impacted countries

The demand for tree nuts has significantly grown in recent years as epidemiological studies and clinical intervention trials demonstrated an inverse relationship between tree nut consumption and chronic diseases. However, mycotoxins are one of the main hazards responsible for increased "Rapid Alert System for Food and Feed" (RASFF) notifications and border rejections on nuts and nut products exported to the E.U. countries in the past few years. Mycotoxins are secondary metabolites that present serious threats to human and animal health. The most prevalent, toxic, and carcinogenic mycotoxins observed in human food and animal feed are the aflatoxins (AFs). This work analyzed notifications from the RASFF on nuts and nut products contaminated with mycotoxins, for a 10-year period from 2011 to 2021. A total of 4752 mycotoxin notifications were published on RASFF for food products worldwide, 63% (n = 3000) were notified in "nuts, nut products and seeds". It was observed that 95% (n = 2669) notifications were due to AFs. Over half of these notifications (52%, n = 1545) were reported for groundnuts, where 29% (n = 441) of the notifications were received for groundnuts from China alone. Border rejection was reported for 91% (n = 2560) of the nuts and nut products which received the notifications from the E.U. countries. This study proffers understanding into the major reasons for RASFF notifications on nuts and nut products exported to E.U. countries. Also, the implications of this issue with some recommendations that could reduce the incidents of notifications for tree nuts have been outlined.

Application of antifungal metabolites from Streptomyces philanthi RL-1-178 for maize grain coating formulations and their efficacy as biofungicide during storage

The major safety risk of maize grain is contamination with mycotoxins. In this study, a maize-coating formulation containing freeze-dried culture filtrate of Streptomyces philanthi RL-1-178 (DCF RL-1-178) was developed and evaluated to prevent the growth of mycotoxins during maize grain storage. In vitro studies using confrontation tests on PDA plates indicated that S. philanthi RL-1-178 inhibited the growth of Aspergillus parasiticus TISTR 3276 (89.0%) and A. flavus PSRDC-4 (95.0%). The maize grain coating formulations containing the DCF RL-1-178 (0, 5, 10, and 15% (v/v)) and the polymer polyvinylpyrrolidone (PVP-K90, 4.0% (w/v)) were tested for their efficacy in In vitro and during 5 months storage. In In vitro assay, maize coating formular containing the optimum concentration (15.0%, v/v) of the DCF RL-1-178 exhibited 54.80% and 54.17% inhibition on the growth of A. parasiticus TISTR 3276 and A. flavus PSRDC-4 respectively. The inhibition was also illustrated by the microstructures of interactions between the coated maize grains with or without the DCF RL-1-178 and the fungal pathogens observed under microscope and SEM. Incorporating the DCF RL-1-178 or fungicidal Metalaxyl® into the polymer PVP-K90 maize grains coating resulted in the complete inhibition of the production of aflatoxin B₁ (analysed by HPLC) by the two aflatoxigenic pathogens after 5 months storage at room temperature. However, the shelf-life was shortened to only 3 months during storage at room temperature with 90% relative humidity. Overall, the application of the 10-15% DCF RL-1-178 into the maize grain coating formular provides a new alternative measure to control the mycotoxins during storage for at least 5 months. The In vitro cell cytotoxicity study showed that a concentration of 15% (v/v) or 1000 μg/mL of the DCF RL-1-178 had a strong cytotoxic effect on Vero cells. These findings indicate that DCF RL-1-178 is a potential biofungicide for controlling mycotoxins contamination in maize seed storage for planting, but not maize grain storage for animal feed.

Detoxification of Aflatoxins in Fermented Cereal Gruel (Ogi) by Probiotic Lactic Acid Bacteria and Yeasts with Differences in Amino Acid Profiles

Toxigenic members of Aspergillus flavus contaminate cereal grains, resulting in contamination by aflatoxin, a food safety hazard that causes hepatocellular carcinoma. This study identified probiotic strains as aflatoxin detoxifiers and investigated the changes to the grain amino acid concentrations during fermentation with probiotics in the presence of either A. flavus La 3228 (an aflatoxigenic strain) or A. flavus La 3279 (an atoxigenic strain). Generally, higher concentrations (p < 0.05) of amino acids were detected in the presence of toxigenic A. flavus La 3228 compared to the atoxigenic A. flavus La 3279. Compared to the control, 13/17 amino acids had elevated (p < 0.05) concentrations in the presence of the toxigenic A. flavus compared to the control, whereas in systems with the atoxigenic A. flavus 13/17 amino acids had similar (p > 0.05) concentrations to the control. There were interspecies and intraspecies differences in specific amino acid elevations or reductions among selected LAB and yeasts, respectively. Aflatoxins B1 and B2 were detoxified by Limosilactobacillus fermentum W310 (86% and 75%, respectively), Lactiplantibacillus plantarum M26 (62% and 63%, respectively), Candida tropicalis MY115 (60% and 77%, respectively), and Candida tropicalis YY25, (60% and 31%, respectively). Probiotics were useful detoxifiers; however, the extent of decontamination was species- and strain-dependent. Higher deviations in amino acid concentrations in the presence of toxigenic La 3228 compared to atoxigenic La 3279 suggests that the detoxifiers did not act by decreasing the metabolic activity of the toxigenic strain.

Molecular Characterization of Aspergillus flavus Strains Isolated from Animal Feeds

Aflatoxin (AF)-producing fungi such as Aspergillus flavus commonly contaminate animal feeds, causing high economic losses. A. flavus is the most prevalent and produces AFB1, a potent mutagen, and carcinogen threatening human and animal health. Aspergillaceae is a large group of closely related fungi sharing number of morphological and genetic similarities that complicate the diagnosis of highly pathogenic strains. We used here morphological and molecular assays to characterize fungal isolates from animal feeds in Southwestern Algeria. These tools helped to identify 20 out of 30 Aspergillus strains, and 15 of them belonged to the Aspergillus section Flavi. Further analyses detected four out of 15 as belonging to Aspergillus flavus-parasiticus group. PCR targeting the AF genes' aflR-aflS(J) intergenic region amplified a single 674 bp amplicon in all four isolates. The amplicons were digested with a BglII endonuclease, and three specific fragments were observed for A. flavus but A. parasitucus lacked two typical fragments. Sequencing data of four amplicons confirmed the presence of the two BglII restriction sites yielding the three fragments, confirming that all four strains were A. flavus. In addition, this analysis illustrated the genetic variability within the A. flavus strains.

Study on dietary intake, risk assessment, and molecular toxicity mechanism of benzo[α]pyrene in college students in China Bashu area

As an extremely strong polycyclic aromatic hydrocarbon carcinogen, benzo[α]pyrene (BaP) is often produced during food processing at high temperatures. Recently, food safety, as well as toxicity mechanism and risk assessment of BaP, has received extensive attention. We first constructed the database of BaP pollution concentration in Chinese daily food with over 104 data items; collected dietary intake data using online survey; then assessed dietary exposure risk; and finally revealed the possible toxicity mechanism through four comparative molecular dynamics (MD) simulations. The statistical results showed that the concentration of BaP in olive oil was the highest, followed by that in fried meat products. The margins of exposure and incremental lifetime cancer risk both indicated that the dietary exposure to BaP of the participants was generally safe, but there were still some people with certain carcinogenic risks. Specifically, the health risk of the core district population was higher than that of the noncore district in Bashu area, and the female postgraduate group was higher than the male group with bachelor degree or below. From MD trajectories, BaP binding does not affect the global motion of individual nucleic acid sequences, but local weak noncovalent interactions changed greatly; it also weakens molecular interactions of nucleic acid with Bacillus stearothermophilus DNA polymerase I large fragment (BF), and significantly changes the cavity structure of recognition interface. This work not only reveals the possible toxicity mechanism of BaP, but also provides theoretical guidance for the subsequent optimization of food safety standards and reference of rational diet.

Preliminary survey of the occurrence of mycotoxins in cereals and estimated exposure in a northwestern region of Mexico

Mycotoxins have several toxicological implications. In the present study, we evaluate the presence of aflatoxin B₁ (AFB₁), ochratoxin A (OTA), and fumonisin (FB₁) in paddy rice, polished rice, and maize from the fields and markets in Nayarit State (Mexico). The results indicated the presence of AFB₁ in 21.21% of paddy rice samples and 11.11% of market maize samples. OTA was present in only 3.03% (one sample) of paddy rice samples. FB₁ was detected in 87.50% and 88.88% of maize samples from field and market, respectively. The estimated human exposure was calculated for FB₁ using the probable daily intake (PDI), which suggested that FB₁ could contribute to the development of diseases through the consumption of contaminated maize. Positive samples indicated that some rice and maize samples were not suitable for human consumption. Further efforts are needed to continue monitoring mycotoxins and update national legislation on mycotoxins accordingly.

Evaluation of the brown alga, Sargassum muticum extract as an antimicrobial and feeding additives

Plant disease administration is difficult due to the nature of phytopathogens. Biological control is a safe method to avoid the problems related to fungal diseases affecting crop productivity and some human pathogenic bacteria. For that, the antimicrobial activity of the seaweed Sargassum muticum methanol and water extracts were investigated against human bacterial pathogens and fungal plant pathogens. By using 70 percent methanol, the seaweed powder was extracted, feeding additives assay, ultrastructure (TEM). Results revealed significant inhibition of S. muticum methanol extract against Salmonella typhi (25.66 mm), Escherichia coli (24.33 mm), Staphylococcus aureus (22.33 mm) and Bacillus subtilis. (19.66 mm), some fungal phytopathogens significantly inhibited Fusarium moniliforme (30.33mm), Pythium ultimum (26.33 mm), Aspergillus flavus (24.36mm), and Macrophomina phaseolina (22.66mm). Phytochemical investigation of S. muticum extract showed the presence of phenolic and flavonoid compounds. Results suggested that there is an appreciable level of antioxidant potential in S. muticum (79.86%) DPPH scavenging activity. Ultrastructural studies of Fusarium moniliforme hypha grown on a medium containing S. muticum extract at concentration 300mg/ml showed a thickening cell wall, disintegration of cytoplasm, large lipid bodies and vacuoles. In conclusion, our study revealed The antibacterial activity of S. muticum extract significantly against some Gram positive, Gram negative bacteria and antifungal activity against some phytopathogenic and some mycotoxin producer fungi. Flavonoids, phenolic play an important role as antioxidants and antimicrobial properties. Such study revealed that S. muticum methanol extract could be used as ecofriendly biocontrol for phytopathogenic fungi and feeding additives to protect livestock products.

Occurrence and Health Risk Assessment of Aflatoxins through Intake of Eastern Herbal Medicines Collected from Four Districts of Southern Punjab-Pakistan

Eastern herbal medicines (HMs) are plant-derived naturally occurring substances with minimum or no industrial processing that have long been used in traditional medicine. Aflatoxins are frequent contaminants of plants. Therefore, these mycotoxins are likely to contaminate HMs and pose a health risk to individuals using them on a regular basis as preventive or curative treatments of various diseases. The present study aimed to determine aflatoxin levels in the most popular Pakistani HM formulations and to assess the health risk associated with the intake of aflatoxins. A total of 400 samples of HM formulations collected from four districts of Punjab were analyzed for the quantification of aflatoxins, out of which 52.5% were found to be contaminated. The average daily dose (ADD) of AFB1 and AFs through the intake of HM formulations ranged between 0.00483 and 0.118 ng/kg bw/day and between 0.00579 and 1.714 ng/kg bw/day, respectively. The margin of exposure (MOE) and population cancer risk ranged from 99.49 to 29378.8 and from 0.00011 to 0.0325 liver cancer cases/105 individuals/year (0.0075-2.455 liver cancer cases/105 individuals/75 years), respectively. Despite the low exposure to aflatoxins from HM formulations in the four studied Punjab (Pakistan) districts, the frequent contamination of the analyzed samples suggests that official measures should be considered to manage the associated risk.

Embryonic exposure to low concentrations of aflatoxin B1 triggers global transcriptomic changes, defective yolk lipid mobilization, abnormal gastrointestinal tract development and inflammation in zebrafish

Aflatoxin B1-contaminated feeds and foods induce various health problems in domesticated animals and humans, including tumor development and hepatotoxicity. Aflatoxin B1 also has embryotoxic effects in different livestock species and humans. However, it is difficult to distinguish between the indirect, maternally-mediated toxic effects and the direct embryotoxicity of aflatoxin B1 in mammals. In the present study, we investigated the aflatoxin B1-induced direct embryotoxic effects in a zebrafish embryo model system combining toxicological, transcriptomic, immunological, and biochemical approaches. Embryonic exposure to aflatoxin B1 induced significant changes at the transcriptome level resulting in elevated expression of inflammatory gene network and repression of lipid metabolism and gastrointestinal tract development-related gene sets. According to the gene expression changes, massive neutrophil granulocyte influx, elevated nitric oxide production, and yolk lipid accumulation were observed in the abdominal region of aflatoxin B1-exposed larvae. In parallel, aflatoxin B1-induced defective gastrointestinal tract development and reduced L-arginine level were found in our model system. Our results revealed the complex direct embryotoxic effects of aflatoxin B1, including inhibited lipid utilization, defective intestinal development, and inflammation.

Aflatoxin contamination in food crops: causes, detection, and management: a review

Mycotoxins are secondary metabolites produced by several fungal species and molds. Under favorable conditions like high temperature and moisture, they contaminate a large number of food commodities and regional crops during pre and post-harvesting. Aflatoxin is the main mycotoxin that harm animal and human health due to its carcinogenic nature. Aflatoxins are mainly released by Aspergillus flavus and Aspergillus parasiticus. AFB1 constitutes the most harmful type of aflatoxins and is a potent hepato-carcinogenic, mutagenic, teratogenic and it suppresses the immune system. To maintain food safety and to prevent aflatoxin contamination in food crops, combined approaches of using resistant varieties along with recommended farming practices should be followed. This review concentrates on various aspects of mycotoxin contamination in crops and recent methods to prevent or minimize the contamination.

Changes in Bacterial Endophyte Community Following Aspergillus flavus Infection in Resistant and Susceptible Maize Kernels

Aspergillus flavus (A. flavus)-mediated aflatoxin contamination in maize is a major global economic and health concern. As A. flavus is an opportunistic seed pathogen, the identification of factors contributing to kernel resistance will be of great importance in the development of novel mitigation strategies. Using V3–V4 bacterial rRNA sequencing and seeds of A. flavus-resistant maize breeding lines TZAR102 and MI82 and a susceptible line, SC212, we investigated kernel-specific changes in bacterial endophytes during infection. A total of 81 bacterial genera belonging to 10 phyla were detected. Bacteria belonging to the phylum Tenericutes comprised 86–99% of the detected phyla, followed by Proteobacteria (14%) and others (<5%) that changed with treatments and/or genotypes. Higher basal levels (without infection) of Streptomyces and Microbacterium in TZAR102 and increases in the abundance of Stenotrophomonas and Sphingomonas in MI82 following infection may suggest their role in resistance. Functional profiling of bacteria using 16S rRNA sequencing data revealed the presence of bacteria associated with the production of putative type II polyketides and sesquiterpenoids in the resistant vs. susceptible lines. Future characterization of endophytes predicted to possess antifungal/ anti-aflatoxigenic properties will aid in their development as effective biocontrol agents or microbiome markers for maize aflatoxin resistance.

A Recent Overview of Producers and Important Dietary Sources of Aflatoxins

Aflatoxins (AFs) are some of the most agriculturally important and harmful mycotoxins. At least 20 AFs have been identified to this date. Aflatoxin B1 (AFB1), the most potent fungal toxin, can cause toxicity in many species, including humans. AFs are produced by 22 species of Aspergillus section Flavi, 4 species of A. section Nidulantes, and 2 species of A. section Ochraceorosei. The most important and well-known AF-producing species of section Flavi are Aspergillus flavus, A. parasiticus, and A. nomius. AFs contaminate a wide range of crops (mainly groundnuts, pistachio nuts, dried figs, hazelnuts, spices, almonds, rice, melon seeds, Brazil nuts, and maize). Foods of animal origin (milk and animal tissues) are less likely contributors to human AF exposure. Despite the efforts to mitigate the AF concentrations in foods, and thus enhance food safety, AFs continue to be present, even at high levels. AFs thus remain a current and continuously pressing problem in the world.

Characteristics, Occurrence, Detection and Detoxification of Aflatoxins in Foods and Feeds

Mycotoxin contamination continues to be a food safety concern globally, with the most toxic being aflatoxins. On-farm aflatoxins, during food transit or storage, directly or indirectly result in the contamination of foods, which affects the liver, immune system and reproduction after infiltration into human beings and animals. There are numerous reports on aflatoxins focusing on achieving appropriate methods for quantification, precise detection and control in order to ensure consumer safety. In 2012, the International Agency for Research on Cancer (IARC) classified aflatoxins B1, B2, G1, G2, M1 and M2 as group 1 carcinogenic substances, which are a global human health concern. Consequently, this review article addresses aflatoxin chemical properties and biosynthetic processes; aflatoxin contamination in foods and feeds; health effects in human beings and animals due to aflatoxin exposure, as well as aflatoxin detection and detoxification methods.

Quercetin protects the buffalo rat liver (BRL-3A) cells from aflatoxin B1-induced cytotoxicity via activation of Nrf2-ARE pathway

Aflatoxin B1 (AFB1) is the most toxic mycotoxin widely presented in agricultural products, and the protective effect of quercetin (QUE), a natural antioxidant, against AFB1-induced cytotoxicity to the buffalo rat liver (BRL-3A) cells was investigated. With an IC50 of 23 μM, AFB1 induced a significant oxidative stress to BRL-3A cells evidenced by a dose-dependent reduction of mitochondria membrane potential (MMP), ATP content, and activities of endogenous antioxidant enzymes along with increased levels of reactive oxygen species (ROS) and lipid peroxidation biomarker of malondialdehyde (MDA). The activity of CYP1A2, the key enzyme to convert AFB1 to reactive AFB1 exo-8,9- epoxide, was also increased, which, probably in together with ROS, led to cell apoptosis with DNA fragmentation, chromatin condensation and increased lactate dehydrogenase release. After the BRL cells were pre-treated by low level QUE (2.5 and/or 5 μM) for 24 h and then exposed to AFB1, the activities of antioxidant enzymes including haeme oxygenase-1, glutathione S-transferase, superoxide dismutase, and the ratio of reduced to oxidised glutathione were significantly increased whereas the levels of intracellular ROS and MDA were reduced. The QUE pre-treatment also increased the levels of MMP, ATP and DNA integrity, and reduced the expression of apoptosis related genes of Bax and Caspase-3. The Western blotting study revealed increased content of phosphorylated Akt and nuclear NF-E2-related factor 2 (Nrf2), indicating an activation of Nrf2-ARE pathway in counteracting oxidative stress and cytotoxicity of AFB1. Thus, the QUE pre-treatment enhanced the anti-stress capacity of the cells through the activation of the Nrf2-ARE pathway, and QUE-based measures could be developed to ameliorate the toxicity caused by AFB1.

Assessment of human health risk based on characteristics of potential toxic elements (PTEs) contents in foods sold in Beijing, China

Metals are generally classified into essential metals groups. Essential metals include copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn), and nonessential metals include cadmium (Cd) and lead (Pb) etc. However, excessive intake of metals even essential metals would have detrimental effect on the body. In this study, seven potential toxic elements (PTEs) (i.e., Cd, Cr, Cu, Fe, Mn, Pb and Zn) and their distribution characteristics in the foods were analyzed as well as the combination of correlation analysis, factor analysis and cluster analysis were constructed. Meanwhile, combined with the dietary consumption data from the Fifth China Total Diet Study (FCTDS), the dietary exposure of PTEs were analyzed and a consequent safety risk assessment was conducted. The main results are as follows: (1) PTE contents in simply-processed samples were found to be lower than those in the highly-processed samples. (2) The average daily intake of the PTEs were about 12.26 (Cd), 153.17 (Cr), 25.16 (Pb) μg/d, 1.90 (Cu), 20.19 (Fe), 7.12 (Mn) and 12.69 (Zn) mg/d, respectively. (3) The total target hazard quotient (TTHQ) was 2.88, which was lower than 10. Therefore, the long-term consumption of these foods combined with the current dietary structure would not have a detrimental effect on the health of residents in Beijing.

Aflatoxins in Food and Feed: An Overview on Prevalence, Detection and Control Strategies

Aflatoxins produced by the Aspergillus species are highly toxic, carcinogenic, and cause severe contamination to food sources, leading to serious health consequences. Contaminations by aflatoxins have been reported in food and feed, such as groundnuts, millet, sesame seeds, maize, wheat, rice, fig, spices and cocoa due to fungal infection during pre- and post-harvest conditions. Besides these food products, commercial products like peanut butter, cooking oil and cosmetics have also been reported to be contaminated by aflatoxins. Even a low concentration of aflatoxins is hazardous for human and livestock. The identification and quantification of aflatoxins in food and feed is a major challenge to guarantee food safety. Therefore, developing feasible, sensitive and robust analytical methods is paramount for the identification and quantification of aflatoxins present in low concentrations in food and feed. There are various chromatographic and sensor-based methods used for the detection of aflatoxins. The current review provides insight into the sources of contamination, occurrence, detection techniques, and masked mycotoxin, in addition to management strategies of aflatoxins to ensure food safety and security.