Aflatoxin B1 contamination in maize samples collected from different geographical regions of India--a multicentre study

Aspergillus flavus and Fusarium verticillioides and Their Main Mycotoxins: Global Distribution and Scenarios of Interactions in Maize

Maize is frequently contaminated with multiple mycotoxins, especially those produced by Aspergillus flavus and Fusarium verticillioides. As mycotoxin contamination is a critical factor that destabilizes global food safety, the current review provides an updated overview of the (co-)occurrence of A. flavus and F. verticillioides and (co-)contamination of aflatoxin B1 (AFB1) and fumonisin B1 (FB1) in maize. Furthermore, it summarizes their interactions in maize. The gathered data predict the (co-)occurrence and virulence of A. flavus and F. verticillioides would increase worldwide, especially in European cold climate countries. Studies on the interaction of both fungi regarding their growth mainly showed antagonistic interactions in vitro or in planta conditions. However, the (co-)contamination of AFB1 and FB1 has risen worldwide in the last decade. Primarily, this co-contamination increased by 32% in Europe (2010-2020 vs. 1992-2009). This implies that fungi and mycotoxins would severely threaten European-grown maize.

Spatiotemporal assessment of post-harvest mycotoxin contamination in rural North Indian food systems

The spatiotemporal trends in aflatoxin B1 (AFB1), fumonisin B1 (FB1), and deoxynivalenol (DON) accumulation were analyzed in a range of food commodities (maize, groundnut, pearl millet, rice, and wheat) in village settings in Unnao, Uttar Pradesh, India. Samples (n = 1549) were collected across six communities and six time points spanning a calendar year and were analyzed for mycotoxins using enzyme-linked immunosorbent assays. AFB1 and FB1 were common across surveyed villages, with moderate to high detection rates (45-75%) observed across commodities. AFB1 levels in maize and groundnuts and FB1 levels in maize and pearl millet frequently exceeded regulatory threshold levels of 15 μg/kg (AFB1) and 2 μg/g (FB1). DON was analyzed in wheat, with 3% of samples yielding detectable levels and none exceeding 1 μg/g. In rice, AFB1 levels were highest in the bran and husk and lower in the kernel. Commodity type significantly influenced AFB1 detection status, while commodity type, season, and visual quality influenced samples' legal status. Storage characteristics and household socioeconomic status indicators did not have significant effects on contamination. No significant effects of any variables on FB1 detection or legal status were observed. Data on mycotoxin contamination, combined with data on local dietary intake, were used to estimate spatiotemporal mycotoxin exposure profiles. Estimated seasonal per capita exposure levels for AFB1 (5.4-39.3 ng/kg body weight/day) and FB1 (~0-2.4 μg/kg body weight/day) exceeded provisional maximum tolerable daily intake levels (1 ng/kg body weight/day for AFB1 and 2 μg/kg body weight/day for FB1) in some seasons and locations. This study demonstrates substantial dietary mycotoxin exposure risk in Unnao food systems and serves as an evidentiary foundation for participatory food safety intervention in the region.

Non-destructive classification and prediction of aflatoxin-B1 concentration in maize kernels using Vis-NIR (400-1000 nm) hyperspectral imaging

Aflatoxin-B1 contamination in maize is a major food safety issue across the world. Conventional detection technique of toxins requires highly skilled technicians and is time-consuming. Application of appropriate chemometrics along with hyperspectral imaging (HSI) can identify aflatoxin-B1 infected maize kernels. Present study was undertaken to classify 240 maize kernels inoculated with six different concentrations (25, 40, 70, 200, 300 and 500 ppb) of aflatoxin-B1 by using Vis-NIR HSI. The reflectance spectral data were pre-processed (multiplicative scatter correction (MSC), standard normal variate (SNV), Savitsky-Golay smoothing and their combinations) and classified using partial least square discriminant analysis (PLS-DA) and k-nearest neighbour (k-NN). PLS model was also developed to predict the concentration of aflatoxin-B1in naturally contaminated maize kernels inoculated with Aspergillus flavus. The potential wavelength (508 nm) was selected based on principal component analysis (PCA) loadings to distinguish between sterile and infected maize kernels. PCA score plots revealed a distinct separation of low contaminated samples (25, 40 and 70 ppb) from highly contaminated samples (200, 300 and 500 ppb) without any overlapping of data. The maximum classification accuracy of 94.7% was obtained using PLS-DA with SNV pre-processed data. Across all the combinations of pre-processing and classification models, the best efficiency (98.2%) was exhibited by k-NN model with raw data. The developed PLS model depicted good prediction accuracy ( R CV 2  = 0.820, SECV = 79.425, RPDCV = 2.382) during Venetian-blinds cross-validation. The results of pixel-wise classification (k-NN) and concentration distribution maps (PLS with raw spectra) were quite close to the result obtained by reference method (HPLC analysis) of aflatoxin-B1 detection.

Aflatoxins: Producing-Molds, Structure, Health Issues and Incidence in Southeast Asian and Sub-Saharan African Countries

This review aims to update the main aspects of aflatoxin production, occurrence and incidence in selected countries, and associated aflatoxicosis outbreaks. Means to reduce aflatoxin incidence in crops were also presented, with an emphasis on the environmentally-friendly technology using atoxigenic strains of Aspergillus flavus. Aflatoxins are unavoidable widespread natural contaminants of foods and feeds with serious impacts on health, agricultural and livestock productivity, and food safety. They are secondary metabolites produced by Aspergillus species distributed on three main sections of the genus (section Flavi, section Ochraceorosei, and section Nidulantes). Poor economic status of a country exacerbates the risk and the extent of crop contamination due to faulty storage conditions that are usually suitable for mold growth and mycotoxin production: temperature of 22 to 29 °C and water activity of 0.90 to 0.99. This situation paralleled the prevalence of high liver cancer and the occasional acute aflatoxicosis episodes that have been associated with these regions. Risk assessment studies revealed that Southeast Asian (SEA) and Sub-Saharan African (SSA) countries remain at high risk and that, apart from the regulatory standards revision to be more restrictive, other actions to prevent or decontaminate crops are to be taken for adequate public health protection. Indeed, a review of publications on the incidence of aflatoxins in selected foods and feeds from countries whose crops are classically known for their highest contamination with aflatoxins, reveals that despite the intensive efforts made to reduce such an incidence, there has been no clear tendency, with the possible exception of South Africa, towards sustained improvements. Nonetheless, a global risk assessment of the new situation regarding crop contamination with aflatoxins by international organizations with the required expertise is suggested to appraise where we stand presently.

Amelioration of Aflatoxin B1-induced gastrointestinal injuries by Eucalyptus oil in rats

Background Eucalyptus oil (EO), derived from Eucalyptus species, possesses vast remedial and healing properties, although its gut health-promoting properties have not been well investigated. In this study, we investigated the chemical composition of a commercial EO formulation and its potential role in protecting against aflatoxin B1 (AfB1)-induced gastrointestinal damage in rats. Methods Male Wistar rats were divided into six groups with eight rats each. Control rats were administered with the vehicle (1% Tween 80) for 14 days, while another group was exposed to two oral doses of AFB1 on days 12 and 14. Two other groups were pre-treated with oral doses of EO (50 and 100 mg/kg b.w.) for 14 consecutive days, along with two oral doses of AfB1 (5 mg/kg b.w.) on days 12 and 14. The remaining two groups were treated with EO alone at the two doses for 14 days. At the end of the experiment, blood samples, stomach and intestinal tissues were collected for measurement of oxidative stress and antioxidant parameters and light microscopic examination. Results Gas chromatography-mass spectrometry analysis revealed Eucalyptol (1, 8-cineole) as the main constituent (67.48%) of the oil. AfB1 administration induced oxidative and inflammatory disturbances, indicated by significantly (p<0.05) increased serum nitric oxide level and myeloperoxidase activity; increased tissue contents of hydrogen peroxide, malondialdehyde and protein carbonyls, accompanied with corresponding histological alterations. AfB1 also induced significant (p<0.05) reductions in glutathione peroxidase and superoxide dismutase (SOD) activities. Treatment with EO produced significant improvements in the biochemical parameters as well as the appearance of the gastric and intestinal mucosa. EO alone, at the two doses tested did not produce any significant changes in the parameters investigated. Conclusion The findings from this study showed that EO demonstrated protective activity against Aflatoxin-induced toxicity in stomach and intestinal tissues and may thus find application in treatment of gastrointestinal disorders.

Histopathological Injuries, Ultrastructural Changes, and Depressed TLR Expression in the Small Intestine of Broiler Chickens with Aflatoxin B₁

To explore AFB₁-induced damage of the small intestine, the changes in structure and expression of TLRs (Toll-like Receptors) in the small intestine of chickens were systematically investigated. Ninety healthy neonatal Cobb chickens were randomized into a control group (0 mg/kg AFB₁) and an AFB₁ group (0.6 mg/kg AFB₁). The crypt depth of the small intestine in the AFB₁ group was significantly increased in comparison to the control chickens, while the villus height and area were evidently decreased, as well as the villus:crypt ratio and epithelial thickness. The histopathological observations showed that the villi of the small intestine exposed to AFB₁ were obviously shedding. Based on ultrastructural observation, the absorptive cells of small intestine in the AFB₁ group exhibited fewer microvilli, mitochondrial vacuolation and the disappearance of mitochondrial cristae, and junctional complexes as well as terminal web. Moreover, the number of goblet cells in the small intestine in the AFB₁ group significantly decreased. Also, AFB₁ evidently decreased the mRNA expression of TLR2-2, TLR4, and TLR7 in the small intestine. Taken together, our study indicated that dietary 0.6 mg/kg AFB₁ could induce histopathological injuries and ultrastructural changes, and depress levels of TLR mRNA in the chicken small intestine.

Aflatoxin B1, zearalenone and deoxynivalenol in feed ingredients and complete feed from different Province in China

BACKGROUND

The current study was carried out to provide a reference for monitory of aflatoxin B₁ (AFB₁), zearalenone (ZEN) and deoxynivalenol (DON) contamination in feed ingredients and complete feeds were collected from different Province in China from 2013 to 2015.

METHODS

A total of 443 feed ingredients, including 220 corn, 24 wheat, 24 domestic distillers dried grains with soluble (DDGS), 55 bran, 20 wheat shorts and red dog, 37 imported DDGS, 34 corn germ meal and 29 soybean meal as well as 127 complete feeds including 25 pig complete feed (powder), 90 pig complete feed (pellet), six duck complete feed and six cattle complete feed were randomly collected from different Province in China, respectively, by high-performance chromatography in combined with UV or fluorescence analysis.

RESULTS

The incidence rates of AFB₁, ZEN and DON contamination of feed ingredients and complete feeds were 80.8, 92.3 and 93.9 %, respectively. The percentage of positive samples for DON ranged from 66.7 to 100 %. Domestic DDGS and imported DDGS presented the most serious contamination AFB₁, ZEN and DON contamination levels of feeds ranged from 61.5 to 100 %, indicated that serious contamination over the studied 3-year period.

CONCLUSION

The current data provide clear evidence that AFB₁, ZEN and DON contamination of feed ingredients and complete feeds in different Province in China is serious and differs over past 3-year. The use of corn, domestic DDGS, imported DDGS and corn germ meal, which may be contaminated with these three mycotoxins, as animal feed may triggered a health risk for animal. Feeds are most contaminated with DON followed by ZEN and AFB₁. Mycotoxins contamination in feed ingredients and complete feeds should be monitored routinely in China.

Role of aflatoxin B1 as a risk for primary liver cancer in north Indian population

OBJECTIVES

The present study was designed to determine whether aflatoxin B1 (AFB1) exposure has any role to play in hepatocellular carcinoma (HCC) patients from northern India.

DESIGN AND METHODS

A total of 266 HCC patients and 251 patients of chronic liver disease without-HCC were enrolled into the study. All samples were screened for serological markers for hepatitis B and C infections and levels of AFB1 in food and urine samples.

RESULTS

A threefold (OR=3.43) and five-fold (OR=5.47) increased risk of HCC was observed amongst HBV infection and AFB1-levels in food and urine samples, respectively. However, a non-significant risk was observed with respect to HCV infection (OR=1.27) and alcohol consumption (OR=1.18). A threefold (OR=3.15) increased risk of HCC was observed amongst cases of non-viral etiology with respect to urinary AFB1.

CONCLUSION

The data provides an exposure and disease risk information for establishing intervention studies to diminish the impact of aflatoxin exposure in Indian population.

Hepatitis B virus-associated hepatocellular carcinoma from India: role of viral genotype and mutations in CTNNB1 (beta-catenin) and TP53 genes

PURPOSE

Chronic hepatitis B virus (HBV) infection is the major risk factor for hepatocellular carcinoma (HCC) in India. Studies from other countries have linked HBV genotype C to a higher risk for HCC. This study was carried out to determine the association between genotype and HCC and also the frequency of mutations in CTNNB1 (beta-catenin) and TP53 genes in HBV-related HCC.

METHODS

Formalin-fixed paraffin-embedded (FFPE) tissues from 20 (15 autopsy, five resected specimens) cases of HBV-associated HCC were examined. Viral genotype was determined by sequencing portions of the HBV S gene using four overlapping PCR amplicons. Exon 3 of CTNNB1 and exon 7 of TP53 were sequenced.

RESULTS

HBV genotyping was possible in 14 of 20 cases; genotype D was most common (n = 11) followed by C (n = 2) and A (n = 1). CTNNB1 mutations were noted in two of 15 amplifiable cases while two of 10 specimens showed TP53 mutations.

CONCLUSIONS

HBV genotype can be ascertained from FFPE sections by sequencing multiple overlapping fragments to avoid the limitation of fragmented DNA. Genotype D was the common genotype in HBV-associated HCC. The very low frequency of TP53 mutation suggests low levels of aflatoxin B₁ exposure. The beta-catenin pathway appears not to be significantly involved in HBV-related HCC in India. However, further larger studies are required to confirm these findings.

Fungal mycoflora and contamination of maize from Vietnam with aflatoxin B1 and fumonisin B1

Twenty five samples of maize intended for human or animal consumption coming from North, Central and South Vietnam were analysed for fungal contamination and for the presence of aflatoxin B1 and fumonisin B1. The total fungal load was found to be greater in maize intended for animal feed than for human consumption with average levels of 4x106 and 7x105 CFU/g, respectively. Identification of fungal strains revealed that Aspergillus was the most frequent genus, found in all maize samples whatever their intended use or their geographic origin. Among the Aspergillus species, A. flavus was the most frequent contaminant, observed in more than 90% of the samples. Other fungal strains found in the Vietnamese maize samples belonged to Penicillium species, Fusarium verticillioides and to the Mucorales, and were found in up to 53, 33 and 23% of the samples, respectively. All samples were tested for both aflatoxin and fumonisin contamination. Aflatoxin B1 was found in 17 samples (68%). Five of these samples showed aflatoxin B1 levels below 10 µg/kg, ten samples were found to be contaminated in a range of 11.3 to 47.2 µg/kg, and 2 samples showed contamination levels of 98.4 and 126.5 µg/kg, respectively. The maize samples for human consumption were found frequently contaminated with aflatoxin B1 (77%), but the level of contamination was lower than those for animal consumption. Fumonisin B1 contamination was found in 8 out of 25 samples (32%). Detected amounts of fumonisin B1 ranged from 0.4 to 3.3 mg/kg.

Aflatoxin B1 contamination in wheat grain samples collected from different geographical regions of India: A multicenter study

In a multicenter study conducted by the Indian Council of Medical Research, 1,646 samples of wheat grain collected from rural and urban areas of 10 states representing different geographical regions of India were analyzed for aflatoxin B1 (AFB1). AFB1 concentrations of > or = 5 microg kg(-1) were recorded in 40.3% of the samples, and concentrations above the Indian permissible regulatory limit of 30 microg kg(-1) were found in 16% of the samples. The proportion of samples with AFB1 concentrations above the Indian regulatory limit ranged from 1.7 to 55.8% in different states, with the minimum in Haryana and the maximum in Orissa. The variation in wheat contamination among states seems to be mainly the result of unsatisfactory storage conditions. Median AFB1 concentrations of 11, 18, and 32 microg kg(-1) were observed in samples from Uttar Pradesh, Assam, and Orissa, respectively; concentrations in other states were <5 microg kg(-1). The maximum AFB1 concentration of 606 microg kg(-1) was observed in a sample from the state of Uttar Pradesh. The calculated probable daily intakes of AFB1 through consumption of contaminated wheat for the population in some states were much higher than the suggested provisional maximum tolerable daily intake. Human health hazards associated with such AFB1 exposure over time cannot be ruled out.

Mycotoxins in poultry feed in Kuwait

A survey was conducted at a poultry feed production unit in Kuwait for mycotoxin contamination in the samples of yellow maize, soybean meal, wheat bran used as raw material and the poultry feed prepared for broiler starter, broiler finisher, and layer mash. Individual aflatoxins were determined by high-pressure liquid chromatography after immunoaffinity column purification. Repeated analysis revealed average aflatoxin concentration in maize at 0.27 ppb (range 0 to 1.69 ppb), soybean meal at 0.20 ppb (range 0 to 1.27 ppb), wheat bran at 0.15 ppb (range 0 to 1.07 ppb), prepared poultry feed for broiler starter at 0.48 ppb (range 0 to 3.26 ppb), broiler finisher at 0.39 ppb (range 0 to 1.05 ppb), and layer mash at 0.21 ppb (range 0 to 1.30 ppb). Other mycotoxins (ochratoxin, fumonisin, deoxynivalenol (DON), and zearalenone), were detected by quantitative enzyme-linked immunosorbent assay. The average levels of ochratoxin A ranged from 4.6 to 9.6 ppb, fumonisin from 1.4 to 3.2 ppm, DON from 0.17 to 0.29 ppm, and zearalenone from 46.4 to 67.6 ppb in various commodities and prepared feed samples. The study revealed the coexistence of determined mycotoxins, although their concentrations in general were found to be lower than the permissible levels, wherever defined, for the poultry feed.

Human aflatoxicosis in developing countries: a review of toxicology, exposure, potential health consequences, and interventions

Aflatoxins are well recognized as a cause of liver cancer, but they have additional important toxic effects. In farm and laboratory animals, chronic exposure to aflatoxins compromises immunity and interferes with protein metabolism and multiple micronutrients that are critical to health. These effects have not been widely studied in humans, but the available information indicates that at least some of the effects observed in animals also occur in humans. The prevalence and level of human exposure to aflatoxins on a global scale have been reviewed, and the resulting conclusion was that approximately 4.5 billion persons living in developing countries are chronically exposed to largely uncontrolled amounts of the toxin. A limited amount of information shows that, at least in those locations where it has been studied, the existing aflatoxin exposure results in changes in nutrition and immunity. The aflatoxin exposure and the toxic affects of aflatoxins on immunity and nutrition combine to negatively affect health factors (including HIV infection) that account for >40% of the burden of disease in developing countries where a short lifespan is prevalent. Food systems and economics render developed-country approaches to the management of aflatoxins impractical in developing-country settings, but the strategy of using food additives to protect farm animals from the toxin may also provide effective and economical new approaches to protecting human populations.

Natural co-occurrence of aflatoxin B1, fumonisin B1 and ochratoxin A in barley and corn foods from Korea

A survey for aflatoxin B1 (AFB1), fumonisin B1 and ochratoxin A (OTA) was conducted on 127 samples that included 30 food-grade barley, 32 barley foods, 18 food-grade corn and 47 corn foods, randomly collected during 1998-99 in Seoul, Korea. The presence of mycotoxins was analysed by direct competitive enzyme-linked immunosorbent assay (ELISA), and most of the positive samples from ELISA were confirmed using high-performance liquid chromatography (HPLC). Recoveries of AFB1 and OTA spiked at 10 ng g(-1) and FB1 spiked at 50 ng g(-1) were 106, 87 and 105% by ELISA, whereas those by HPLC were 80, 79 and 84%, respectively. Detection limits by ELISA for AFB1, FB1 and OTA were 1, 5 and 5 ng g(-1), and those by HPLC were 0.6, 35 and 1 ng g(-1). Naturally occurring AFB1, FB1 and OTA were found in 4/32 (12%), 2/32(6%) and 4/32 (12%) samples of barley foods with an average of 26, 16 and 9 ng g(-1), respectively. AFB1 and FB1 in corn foods were detected in 4/47 (8%) and 9/47 (19%) samples with the average being 20 and 74 ng g(-1), while no OTA was found in any corn foods samples. No AFB1, FB1 or OTA was detected in any of food-grade barley and corn samples. This is the first report on the natural co-occurrence of AFB1 and FB1 in barley and corn foods as well as on surveillance of OTA in Korea.

Isolation of aflatoxigenic strains of Aspergillus and detection of aflatoxin B1 from feeds in India

In a preliminary study, 256 feed samples collected from different parts of Northern India were examined for the presence of aflatoxigenic strains of Aspergillus favus/parasiticus and for detection of Aflatoxin B1 (AFB1). Out of 198 A. flavus and 15 A. parasiticus strains isolated, 76% and 86% respectively, were found to be toxigenic. Aflatoxin B1 content of these feeds, as estimated by thin layer chromatography (TLC) and enzyme linked immunosorbent assay (ELISA) were very high (average 0.412+/-0.154 ppm) in comparison to the permissible Indian regulation level (0.03 ppm). Seasonal variation of incidence and level of toxin in feed was recorded and it was high during monsoon/post monsoon period.

Natural occurrence of aflatoxins in Korean meju

Aflatoxin B1 (AFB1) was found in 35 of 60 (58.3%) meju samples with an average concentration of 7.3 ng/g by ELISA. Contamination of AFB1 was confirmed in 25 of 60 samples (41.6%) using HPLC, with an average concentration of 6.9 ng/g. Mean recoveries from meju ranged from 107% to 170% for AFB1 using ELISA at a spiking range of 1 to 50 ng/g. Over the same range, recoveries using HPLC were from 70% to 83%. The levels of AFB1 determined by ELISA and by HPLC demonstrated a close relationship between the two methods (r2 = 0.9324) employed in this study. In order to evaluate the potential health risks of AFB1 on Koreans consuming meju, we calculated the estimated probable daily intake (PDI) based on the average contamination levels and compared it with the estimated tolerable daily intake (TDI). The PDIs of AFB1 from kanjang and dwenjang were determined to be 0.04 and 0.21 ng/kg bw/day, respectively, and were higher than TDIs.