Control Of Aflatoxin Contamination Research Articles

The GATA factor AreB regulates nitrogen metabolism, fungal development, and aflatoxin production in Aspergillus flavus.

Nitrogen is important for fungal growth and development, and the GATA transcription factor AreA has been widely studied as a key regulator of nitrogen catabolite repression (NCR) in many fungi. However, AreB, another GATA transcription factor in the NCR pathway, remains less studied, and its role in Aspergillus flavus is still unclear. In this study, we characterized areB in A. flavus and investigates its role in regulating nitrogen utilization, fungal growth, and aflatoxin production. The areB gene produces three transcripts, with areB-α being the most abundantly expressed, particularly under nitrogen-limited conditions. Gene expression analysis via qPCR confirmed that areB acts as a negative regulator of NCR, as its deletion led to the upregulation of NCR-related genes under nitrogen-limiting conditions. Gene function analysis of areB revealed that its deletion impaired hyphal growth, reduced conidia production, and delayed conidial germination. Additionally, deletion of areB led to increased aflatoxin production, particularly under less favorable nitrogen sources, while overexpression of areB reduced aflatoxin levels. Furthermore, areB influenced sclerotia formation in a nitrogen-source-dependent manner. These findings reveal the multifaceted role of areB in nitrogen regulation, fungal development, and secondary metabolism, offering insights for controlling aflatoxin contamination and fungal growth.

Aflatoxin control strategies for traditional Korean doenjang: Fermentation process improvements and industrial application

Meju, a raw material used in fermented soybean paste, doenjang, is often contaminated with aflatoxins; thus, controlling aflatoxin contamination in meju and doenjang is crucial. A one-variable-at-a-time (OVAT) approach revealed an inhibitory effect on aflatoxin production by Aspergillus flavus in cooked soybeans treated with soaking solutions containing NaCl (≥ 5 %) and vinegar (≥ 1 %). Additionally, a fermentation temperature (40 °C) negatively affected aflatoxin production. Based on OVAT and response surface methodology, three soaking solutions: I (0.1 % vinegar + 2.5 % salt), II (0.1 % vinegar + 3.75 % salt), and III (0.1 % vinegar + 5 % salt) were prepared and applied at the industrial level of meju production. Meju prepared from soybeans treated with these soaking solutions, coded Meju-I, Meju-II, and Meju-III, respectively, exhibited significant reductions (96.03–100 %) in aflatoxin production compared with control meju (Meju-C). Similar microbial counts and genus-level microbial diversity were observed in Meju-C and Meju-I, with Bacillus, Enterococcus, Klebsiella, and Aspergillus as the predominant microbial genera. Furthermore, sensory analysis of doenjang prepared from Meju-C and Meju-I yielded no significant differences, supporting the applicability of soaking solution I to regulate aflatoxin levels in meju and doenjang at industrial scale.

Aflatoxins in Wheat Grains: Detection and Detoxification through Chemical, Physical, and Biological Means.

Wheat (Triticum aestivum L.) is an essential food crop in terms of consumption as well as production. Aflatoxin exposure has a widespread public health impact in economically developing nations, so there is a need to establish preventive techniques for these high-risk populations. Pre-harvest and post-harvest practices are the two strategies used to control aflatoxin contamination, which include the use of genetically modified crops that show resistance against Aspergillus infection, the use of pesticides, changing the planting and harvesting time of crops, and physical, chemical, and biological methods. In this research, aflatoxin detection and quantification were performed in different wheat varieties to determine quantitative differences in comparison to the European Commission's limit of 4 ppb aflatoxins in wheat. TLC for qualitative and the ELISA kit method for quantitative analysis of aflatoxins were used. Out of 56 samples, 35 were found contaminated with aflatoxins, while the remaining 21 samples did not show any presence of aflatoxins. Out of the 35 contaminated samples, 20 samples showed aflatoxin contamination within the permissible limit, while the remaining 15 samples showed aflatoxin concentration beyond the permissible level, ranging from 0.49 to 20.56 ppb. After quantification, the nine highly contaminated wheat samples were detoxified using physical, chemical, and biological methods. The efficiency of these methods was assessed, and they showed a significant reduction in aflatoxins of 53-72%, 79-88%, and 80-88%, respectively. In conclusion, the difference in aflatoxin concentration in different wheat varieties could be due to genetic variations. Furthermore, biological treatment could be the method of choice for detoxification of aflatoxins in wheat as it greatly reduced the aflatoxin concentration with no harmful effect on the quality of the grains.

Molecular Docking Analysis of Potential Fatty Acid Compounds from Tiger Milk Mushroom (Lignosus rhinocerus (Cooke) Ryvarden) Against Thioesterase Domain of Polyketide Synthase Enzyme in Aspergillus ssp.

Fungal growth, particularly from species like Aspergillus, poses significant economic, agricultural, and health risks to humans due to aflatoxin production. Consequently, inhibiting aflatoxin synthesis has become a critical objective. In this study, researchers targeted the thioesterase (TE) domain of the Polyketide synthase enzyme for in silico docking experiments using AutoDock Vina. The aim was to identify potential inhibitors that could selectively target the TE domain. Various fatty acids from Lignosus rhinocerus were employed for this purpose, including lauric acid, decanoic acid, tetradecanoic acid-methyl ester, hexadecanoic acid, propionic acid, palmitic acid, stearic acid, and oleic acid. Decanoic acid showed promising results with binding energy close to the standard, forming two conventional hydrogen bonds, and exhibiting hydrophobic interactions during docking with the 3ILS protein. These findings suggest that decanoic acid could be utilized for inhibiting and controlling aflatoxin contamination in agricultural crops.

Optimal control and cost effectiveness analysis of contamination associated with aflatoxins in maize kernels, livestock and humans

Aflatoxin contamination poses a significant challenge in food safety and security as it affects both health of consumers and supply chains. Due to health impacts associated with aflatoxin contamination, countries have set standards and restrictions for importing food crops and animal feed, resulting in greater economic losses to farmers, transporters, and crop processors. Three controls, namely good farming practices, biological control and public education and awareness campaigns, have been mostly used in countries where aflatoxin contamination has occurred. Since resources are scarce, there is a need to find the optimal and cost-effective strategy to reduce the burden on farmers. This study aimed to find optimal and cost-effective control strategy to mitigated aflatoxin contamination in maize kernels, livestock and humans. A deterministic model was developed and analyzed for studying the impact of implementing three time dependent controls on the dynamics and control of aflatoxin contamination in maize kernels, livestock and humans. We use optimal control theory to find the necessary conditions for existence of the optimal controls and to determine the optimal strategy for controlling the aflatoxin contamination. We also carry out cost-effectiveness analysis through Incremental Cost Effective Ratio (ICER) to obtain the most effective strategy. Simulation results for the optimal control problem suggest that strategy which involve implementation of all controls performs well than other strategies in controlling the aflatoxin contamination in maize kernels, livestock and humans. Therefore, to control aflatoxin contamination initiatives should focus on good farming practices, biological control and public education and awareness campaigns.

Research Progress Related to Aflatoxin Contamination and Prevention and Control of Soils.

Aflatoxins are potent carcinogenic compounds, mainly produced by fungi species of the genus Aspergillus in the soil. Because of their stability, they are difficult to remove completely, even under extreme conditions. Aflatoxin contamination is one of the main causes of safety in peanuts, maize, wheat and other agricultural products. Aflatoxin contamination originates from the soil. Through the investigation of soil properties and soil microbial distribution, the sources of aflatoxin are identified, aflatoxin contamination is classified and analysed, and post-harvest crop detoxification and corresponding contamination prevention measures are identified. This includes the team's recent development of the biofungicide ARC-BBBE (Aflatoxin Rhizobia Couple-B. amyloliquefaciens, B. laterosporu, B. mucilaginosus, E. ludwiggi) for field application and nanomaterials for post-production detoxification of cereals and oilseed crops, providing an effective and feasible approach for the prevention and control of aflatoxin contamination. Finally, it is hoped that effective preventive and control measures can be applied to a large number of cereal and oilseed crops.

Pistachio Male Inflorescences as an Alternative Substrate for the Application of Atoxigenic Strains of Aspergillus flavus.

Aflatoxins are carcinogens mainly produced by Aspergillus flavus and A. parasiticus in susceptible crops, including pistachio. The primary inoculum sources of these pathogens are plant debris in the orchard soils. In Californian fields, one approach to controlling aflatoxin contamination is based on releasing the atoxigenic strain of A. flavus AF36 in inoculated (coated) sorghum grains (AF36 Prevail). However, this control method can fail due to poor sporulation of the AF36 strain or sorghum grain losses due to predation. In 2008 and 2018, we showed that toxigenic and atoxigenic isolates of Aspergillus spp. frequently colonized fallen inflorescences of male pistachio trees. Under controlled conditions, strain AF36 profusely colonized pistachio male inflorescences when humidity was higher than 90%. However, there were significant differences between types of inflorescence (aerial > fallen). In 2016, we considerably (P = 0.015) increased the population of AF36 on the canopies of trees when fallen inflorescences were inoculated with AF36, compared with untreated trees. In 2017 and 2018, these differences were not detected (P > 0.05) due to cross-contamination of strain AF36 between seasons and neighboring plots. In any case, the density of AF36 spores on the canopy of the inflorescence-treated trees was similar (P > 0.05) to that on trees treated with the commercial product. Here, we present a new method for applying strain AF36 based on using a natural, abundant, and uniformly distributed substrate in pistachio fields, and we discuss how it can be improved. Furthermore, our results indicate that, in pistachio orchards where biocontrol practices are not conducted, eliminating this important source of toxigenic Aspergillus inoculum is recommended.

Food handling practices, the prevalence of aflatoxin dietary exposure and its associated factors among children aged 6–23 months in Bukombe District, Tanzania

BackgroundComplementary foods are provided to newborns and early children to replace breast milk, which, after six months of exclusive breastfeeding, is no longer adequate to meet the child's nutritional needs. However, foods like dairy, grains like maize, sorghum, and millet, as well as nuts like groundnuts, which are frequently suggested as supplemental foods have all been linked to aflatoxin contamination. Understanding how caregiver preparation and storage practices of complementary flour affect children's aflatoxin exposure is crucial. ObjectiveTo determine the prevalence of dietary exposure to aflatoxin and its associated factors in children aged 6–23 months complemented with cereal-based foods in the Bukombe District of Geita Region in Tanzania. MethodologyAn analytical cross-sectional study was used to survey 342 households of children aged 6–23 months. Fifty complementary flour samples from 50 of the total households were chosen at random and tested for aflatoxin using the HPLC technique and standard methods. A semi-structured questionnaire was used to assess parents'/caregivers' food handling and preparation practices and the amount of food consumed. The obtained results were used to estimate aflatoxin dietary exposure of children in the study. ResultsMost of the children (86%) were exposed to aflatoxin through diet with a median value of 0.3 μg/kg-bw/day mainly linked to age and breastfeeding status. The majority of the exposed (86%) were above the reference limit of 0.04 μg/kg-bw/day. Most parents (98.5%) chose maize as the main component of complementary flour, either on its own or mixed with other cereals and winnowing and dehulling as the most and least common practices with the proportion of 78.9% and 9.4% respectively. Furthermore, a majority (88%) of flour samples were contaminated with aflatoxin B1 and total aflatoxin with log mean values of 1.2 ± 0.81 and 1.5 ± 0.68 μg/kg respectively which were above the Tanzania reference limit of 5 μg/kg and 10 μg/kg respectively. Contamination was significantly (p < 0.05) associated with location (Fisher's exact value = 6.68, p = 0.036), source of cereals (Fisher's exact value = 56.4 p = 0.025), and storage time (Fisher exact value = 23.8, p < 0.001). ConclusionIn view of the findings, aflatoxin contamination in flours used for complementary feeding was beyond tolerable limits, hence increasing the risk of children's dietary exposure. This suggests that strengthening strategies to control aflatoxin contamination of maize throughout the food chain and teaching parents about preparation and storage methods that reduce aflatoxin in cereals/flour are important.

Performance of testers with contrasting provitamin A content to evaluate provitamin A maize for resistance to Aspergillus flavus infection and aflatoxin production.

In sub-Saharan Africa (SSA), millions of people depend on maize as a primary staple. However, maize consumers in SSA may be exposed to malnutrition due to vitamin A deficiency (VAD) and unsafe aflatoxin levels, which can lead to serious economic and public health problems. Provitamin A (PVA) biofortified maize has been developed to alleviate VAD and may have additional benefits such as reduced aflatoxin contamination. In this study, maize inbred testers with contrasting PVA content in grain were used to identify inbred lines with desirable combining ability for breeding to enhance their level of resistance to aflatoxin. Kernels of 120 PVA hybrids generated by crossing 60 PVA inbreds with varying levels of PVA (5.4 to 51.7 µg/g) and two testers (low and high PVA, 14.4 and 25.0 µg/g, respectively) were inoculated with a highly toxigenic strain of Aspergillus flavus. Aflatoxin had a negative genetic correlation with β-carotene (r= -0.29, p < 0.0001) and PVA (r = -0.23, p < 0.0001), indicating that hybrids with high PVA content accumulated less aflatoxin than those with low to medium PVA. Both general combining ability (GCA) and specific combining ability (SCA) effects of lines and testers were significant for aflatoxin accumulation, number of spores, PVA, and other carotenoids, with additive gene actions playing a prominent role in regulating the mode of inheritance (GCA/SCA ratio >0.5). Eight inbreds had combined significant negative GCA effects for aflatoxin accumulation and spore count with significant positive GCA effects for PVA. Five testcrosses had combined significant negative SCA effects for aflatoxin with significant positive SCA effects for PVA. The high PVA tester had significant negative GCA effects for aflatoxin, lutein, β-carotene, and PVA. The study identified lines that can be used as parents to develop superior hybrids with high PVA and reduced aflatoxin accumulation. Overall, the results point out the importance of testers in maize breeding programs to develop materials that can contribute to controlling aflatoxin contamination and reducing VAD.

Efficient Inhibition of Aspergillus flavus to Reduce Aflatoxin Contamination on Peanuts over Ag-Loaded Titanium Dioxide.

Peanuts are susceptible to aflatoxins produced by Aspergillus flavus. Exploring green, efficient, and economical ways to inhibit Aspergillus flavus is conducive to controlling aflatoxin contamination from the source. In this study, Ag-loaded titanium dioxide composites showed more than 90% inhibition rate against Aspergillus flavus under visible light irradiation for 15 min. More importantly, this method could also reduce the contaminated level of Aspergillus flavus to prevent aflatoxins production in peanuts, and the concentrations of aflatoxin B1, B2, and G2 were decreased by 96.02 ± 0.19%, 92.50 ± 0.45%, and 89.81 ± 0.52%, respectively. It was found that there are no obvious effects on peanut quality by evaluating the changes in acid value, peroxide value, and the content of fat, protein, polyphenols, and resveratrol after inhibition treatment. The inhibition mechanism was that these reactive species (•O2-, •OH-, h+, and e-) generated from photoreaction destroyed cell structures, then led to the reduced viability of Aspergillus flavus spores. This study provides useful information for constructing a green and efficient inhibition method for Aspergillus flavus on peanuts to control aflatoxin contamination, which is potentially applied in the field of food and agri-food preservation.

Determination of Aflatoxin M1 in Buffalo Milk and Products

This study aimed to investigate the presence of Aflatoxin M1 (AFM1) in raw buffalo milk and buffalo milk products such as cheese, yogurt, cream, and ice cream by ELISA technique. In the study, 175 samples were investigated, and it was determined that 146 (83.43%) of the samples had AFM1 concentrations below the LOD (limit of detection) value. In 29 samples (16.57%), the AFM1 concentration exceeded the LOD value, and in 7 (4%) of these, the AFM1 concentration was above the legal limits (50 ng/L). While AFM1 was not detected in raw buffalo milk samples, the presence of AFM1 in cheese, yogurt, cream, and ice cream samples was found to be 2.85%, 2.85%, 62.85%, and 14.3%, respectively. 2.85% of cheese samples and 17.1% of cream samples were found contaminated with AFM1 above the allowed legal limits (50 ng/L). As a result, it was determined that the potential for exposure to AFM1 by consuming buffalo cream was higher than the consumption of buffalo milk and other buffalo milk products. However, the detection of AFM1 above legal limits in buffalo milk products poses a serious risk to public health. Therefore, it is extremely necessary for public health to develop effective monitoring programs to control aflatoxin contamination in milk and new strategies to maintain inspections.

Farmer's knowledge and suggested approaches for controlling aflatoxin contamination of raw milk in Pakistan.

Monitoring of aflatoxin levels in milk is often complicated in developing countries due to the dominance of informal markets channeling milk in raw form. Farmer's awareness and voluntary participation in aflatoxin mitigation can be critical in such scenarios. Therefore, the present study was conducted to understand the perceptions of dairy farmers about aflatoxins and link it with aflatoxin mitigation programs on milk in Pakistan. Information was collected from 450 peri-urban dairy farmers in seven cities using questionnaires. Majority (77.9%) of the farmers were aware of the negative impact of moldy feed on animal health. However, only 40.6% of the farmers were aware of the transferability of the toxins from moldy feed to milk. The farmers had almost no awareness of aflatoxins as 95% never heard of the term. After receiving an onsite briefing on effects of the toxin on animal and human health, and its transferability to milk, 98.3% farmers showed willingness to buy aflatoxin-safe feedstuffs, while 88.5% showed willingness to control aflatoxin in milk. Around half of the farmers considered aflatoxin control programs as affordable. On average, farmers agreed to pay 10.1% higher price for aflatoxin certified oilseed cakes. Availability of feedstuffs certified of low aflatoxin content was suggested by 22% of the participants as the critical step in reducing aflatoxins in milk. Other important suggestions included; subsidy on quality feeds (18%), raising awareness (18%), and legislation and monitoring (16%). The present results suggest that the current practice of milk monitoring in the country can yield desirable results only if it is coupled with feed certification programs ensuing availability of aflatoxin-safe feeds. Further, awareness can positively impact participation of producers in aflatoxin control programs. In this regard, awareness about effects of aflatoxins on animal health was found to be a more powerful trigger of voluntary control compared with the awareness of the toxin's transferability to milk.

Application of Non-Aflatoxigenic Aspergillus flavus for the Biological Control of Aflatoxin Contamination in China.

Biological control through the application of competitive non-aflatoxigenic Aspergillus flavus (A. flavus) to the soil during peanut growth is a practical method for controlling aflatoxin contamination. However, appropriate materials need to be found to reduce the cost of biocontrol products. In this study, a two-year experiment was conducted under field conditions in China, using a native non-aflatoxigenic strain to explore its effect. After three months of storage under high humidity, aflatoxin levels remained low in peanuts from fields treated with the biocontrol agent. Three types of substrates were tested with the biocontrol agent: rice grains, peanut meal (peanut meal fertilizer) and peanut coating. Compared to untreated fields, these formulations resulted in reductions of 78.23%, 67.54% and 38.48%, respectively. Furthermore, the ratios of non-aflatoxigenic A. flavus recovered in the soils at harvest in the treated fields were between 41.11% and 96.67% higher than that in untreated fields (25.00%), indicating that the rice inoculum was the most effective, followed by the peanut meal fertilizer and peanut coating. In 2019, the mean aflatoxin content of freshly harvested peanuts in untreated fields was 19.35 µg/kg higher than that in the fields treated with 7.5 kg/ha rice inoculum, which was 1.37 µg/kg. Moreover, no aflatoxin was detected in the two other plots treated with 10 and 15 kg/ha rice inoculum. This study showed that the native Chinese non-aflatoxigenic strain of A. flavus (18PAsp-zy1) had the potential to reduce aflatoxin contamination in peanuts. In addition, peanut meal can be used as an alternative substrate to replace traditional grains, reducing the cost of biocontrol products.

Inhibition of Essential Oils on Growth of Aspergillus flavus and Aflatoxin B1 Production in Broth and Poultry Feed.

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.

Phosphomannose Isomerase Is Involved in Development, Stress Responses, and Pathogenicity of Aspergillus flavus.

ABSTRACTAspergillus flavus causes invasive aspergillosis in immunocompromised patients and severe contamination of agriculturally important crops by producing aflatoxins. The fungal cell wall is absent in animals and is structurally different from that of plants, which makes it a potential antifungal drug target due to its essentiality for fungal survival. Mannose is one of the important components in the fungal cell wall, which requires GDP-mannose (GDP-Man) as the primary donor. Three consecutive enzymes, namely, phosphomannose isomerase (PMI), phosphomannose mutase (PMM), and GDP-mannose phosphorylase (GMPP), are required for GDP-Man biosynthesis. Thus, PMI is of prime importance in cell wall biosynthesis and also has an active role in sugar metabolism. Here, we investigated the functional role of PMI in A. flavus by generating a pmiA-deficient strain. The mutant required exogenous mannose to survive and exhibited reduced growth rate, impaired conidiation, early germination, disturbance in stress responses, and defects in colonization of crop seeds. Furthermore, attenuated virulence of the mutant was documented in both Caenorhabditis elegans and Galleria mellonella infection models. Our results suggested that PMI plays an important role in the development, stress responses, and pathogenicity of A. flavus and therefore could serve as a potential target for battling against infection and controlling aflatoxin contamination caused by A. flavus.IMPORTANCE Aspergillus flavus is a common fungal pathogen of humans, animals, and agriculturally important crops. It causes invasive aspergillosis in humans and also produces highly carcinogenic mycotoxins in postharvest crops that threaten food safety worldwide. To alleviate or eliminate the threats posed by A. flavus, it is necessary to identify genes involved in pathogenicity and mycotoxin contamination. However, little progress has been made in this regard. Here, we focused on PMI, which is the first enzyme involved in the biosynthesis pathway of GDP-Man and thus is important for cell wall synthesis and protein glycosylation. Our study revealed that PMI is important for growth of A. flavus. It is also involved in conidiation, germination, morphogenesis, stress responses, and pathogenicity of A. flavus. Thus, PMI is a potent antifungal target to curb the threats posed by A. flavus.

Afper1 contributes to cell development and aflatoxin biosynthesis in Aspergillus flavus

Aspergillus flavus contaminates crops and produces carcinogenic aflatoxins that pose severe threat to food safety and human health. To identify potential targets to control aflatoxin contamination, we characterized a novel Afper1 protein, which regulates cell development and secondary metabolite biosynthesis in A. flavus. Afper1 is localized in the nucleus and is required for hyphal growth, conidial and sclerotial production, and responses to osmotic stress and essential oils such as cinnamaldehyde and thymol. More importantly, aflatoxin production was impaired in the Afper1 deletion mutant. Proteomics analysis revealed that extracellular hydrolases and proteins involved in conidial development, endoplasmic reticulum (ER) homeostasis, and aflatoxin biosynthesis were differentially regulated in ΔAfper1. Unexpectedly, enzymes participated in reactive oxygen species (ROS) scavenging, including catalase (catA, catB) and superoxide dismutase (sodM) were significantly downregulated, and the ROS accumulation and sensitivity to hydrogen peroxide were confirmed experimentally. Additionally, Afper1 deletion significantly upregulated heterochromatin protein HepA and downregulated acetyltransferases involved in heterochromatin formation. Accompanying ROS accumulation and chromatin remodeling, proteins related to aflatoxins, ustiloxin B and gliotoxin were downregulated. These results implied that Afper1 deletion affected chromatin remodeling and disturbed ER homeostasis, leading to ROS accumulation, and ultimately resulting in defective growth and impaired secondary metabolite biosynthesis.

Aflatoxin Contamination, Its Impact and Management Strategies: An Updated Review.

Aflatoxin, a type of mycotoxin, is mostly produced by Aspergillus flavus and Aspergillus parasiticus. It is responsible for the loss of billions of dollars to the world economy, by contaminating different crops such as cotton, groundnut, maize, and chilies, and causing immense effects on the health of humans and animals. More than eighteen different types of aflatoxins have been reported to date, and among them, aflatoxins B1, B2, G1, and G2 are the most prevalent and lethal. Early detection of fungal infection plays a key role in the control of aflatoxin contamination. Therefore, different methods, including culture, chromatographic techniques, and molecular assays, are used to determine aflatoxin contamination in crops and food products. Many countries have set a maximum limit of aflatoxin contamination (2–20 ppb) in their food and agriculture commodities for human or animal consumption, and the use of different methods to combat this menace is essential. Fungal infection mostly takes place during the pre- and post-harvest stage of crops, and most of the methods to control aflatoxin are employed for the latter phase. Studies have shown that if correct measures are adopted during the crop development phase, aflatoxin contamination can be reduced by a significant level. Currently, the use of bio-pesticides is the intervention employed in many countries, whereby atoxigenic strains competitively reduce the burden of toxigenic strains in the field, thereby helping to mitigate this problem. This updated review on aflatoxins sheds light on the sources of contamination, and the on occurrence, impact, detection techniques, and management strategies, with a special emphasis on bio-pesticides to control aflatoxins.

Anti-aflatoxigenic nano-emulsions based on Monarda didyma and Neopallasia pectinata essential oils as novel green agent for food preservation

Food-borne aflatoxins impede the path of current agriculture and worsened the food safety problem, thus researches on prevention and detoxification of aflatoxins by biological, chemical and physical technologies have become hot spots in food safety and agriculture fields. Recently, efficient preservative based on phytochemicals with nano formulation is considered a versatile and green approach to control aflatoxin contamination. In this study, fabrication of a series of nano-emulsions based on American mint and pectinata essential oils via high pressure homogenization is presented. Their morphology and stability via dynamic light scattering and scanning electron microscopy were explored. All these nano-emulsions, namely MNEO 1–5, exhibited obviously growth inhibition effect towards Aspergillus aflatoxiformans with ED50 values of 5.18 ± 0.56, 4.70 ± 0.83, 6.37 ± 0.55, 6.65 ± 0.79 and 8.89 ± 0.90 mg g−1, respectively. Moreover, cell membrane damage assays showed that interactions between MNEO and cell membrane of A. aflatoxiformans resulted in increased electronic conductivity and cell death. To demonstrate prevention effect, a storage simulation experiment was designed on peanut seeds to determine the AFB1 control efficacy of nano-emulsions in hot and wet environments, and both the nano-emulsions displayed remarkable prevention effect after the preservation with AFB1 protection at 86.06–94.00%. For realistic management of pathogens and mycotoxins, bio-active EOs with nano-formulation capable of adapting to complex environment may help to innovate important key source technologies for food processing and preservation in future.

Biocontrol efficacy of atoxigenic Aspergillus flavus strains against aflatoxin contamination in peanut field in Guangdong province, South China

ABSTRACT Application of atoxigenic strains of Aspergillus flavusto soils is the most successful aflatoxin biological control approach. The objective of this study was to evaluate the efficacies of native non-aflatoxin producing (atoxigenic) strains as a biocontrol agent in peanut field in China. The competitive atoxigenic A. flavus strains (JS4, SI1and SXN) isolated from different crops, in China were used for field evaluation. The strains applied during the growing season (June – October, 2016) in the field at rate of 25 kg inoculum/hectare. The colonization of these biocontrol agents has been investigated and the population of A. flavus communities in soil were determined. The incidences of toxin producing (toxigenic) A. flavus strains and aflatoxin contamination in peanuts were also determined. Treated plots produced significant reductions in the incidence of toxigenic isolates of A. flavus in soil. However, the total fungal densities were not significantly different (p > 0.05) after treatments. Large percentage of aflatoxin reductions, ranging from 82.8% (SXN) up to 87.2% (JS4) were recorded in treated plots. Generally, the results suggest that the strategy can be used to control aflatoxin contamination and continuous evaluation should be done.

The microbial population structure and function of peanut peanut and their effects on aflatoxin contamination

Aflatoxin is a strong carcinogenic and toxic fungal toxin produced by Aspergillus flavus and other Aspergillus species, and can seriously threaten the health of consumers, thus becoming a global concern. Aflatoxin in agricultural products are closely related to biogeography and symbiotic microorganisms. It is not fully clear that how biogeography affects the assembly process of A. flavus and symbiotic microorganisms on plant. In this study, we analyzed the structure and assembly process of fungi and bacteria on the peanut. We also performed metagenome analysis to assess the relationships between functional genes and metabolic pathways in the microorganisms, aflatoxin and biogeography. Finally, our data showed that inoculation of beneficial microorganisms isolated from the healthy peanut-associated microbiome could significantly inhibit the enrichment of A. flavus and the production of aflatoxin in inoculated plants. Our results indicate that biogeography can significantly influence the assembly process of microorganisms, the activation of functional genes and metabolic pathways, the enrichment of aflatoxin-producing fungi. Manipulation of the peanut-associated microbiome, for instance, by inoculating peanut with beneficial strains, has potential to promote plant health. This will provide us with new ideas and perspectives on the early warning and effective prevention and control of aflatoxin contamination in agricultural products.