The natural occurrence of fumonisins in Brazilian corn kernels

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.

Prediction of fumonisins B1 and B2 in corn distiller's dried grains with solubles through near-infrared reflectance spectroscopy

BACKGROUND

Distiller's dried grains with solubles (DDGS) are coproducts of the biofuel industries that use corn as raw material. This cereal is commonly contaminated by mycotoxins, including fumonisins (FBs), which can pose a serious health threat to humans and animals. Corn DDGS are typically used as a protein-rich animal feed. As mycotoxins from the original cereal grains become concentrated in DDGS, mycotoxicological monitoring is highly required before their use as ingredient in the industry.

RESULTS

This work aimed to develop a methodology for predicting fumonisins B₁ (FB₁ ) and B₂ (FB₂ ) in corn DDGS using near-infrared reflectance spectroscopy (NIRS) technology associated with chemometric methods. One hundred and ninety corn DDGS samples originating from Brazilian ethanol plants and feed mills were included in this assessment. Two datasets were created: one for calibration (132 samples) and another for external validation (58 samples). Partial least squares regression and a cross-validation approach were applied to build the models. Liquid chromatography coupled to tandem mass spectrometry was used as the reference methodology. Calibration results of correlation coefficient and residual prediction deviation for FB₁ and FB₂ were, respectively, 0.90 and 0.88; and 2.16 and 2.06.

CONCLUSION

Values of the external validation dataset were compared and no statistical difference was found between groups, indicating a satisfactory predictive ability and confirming the potential of NIRS to predict fumonisins in corn DDGS. © 2022 Society of Chemical Industry.

Variation of Deoxynivalenol Levels in Corn and Its Products Available in Retail Markets of Punjab, Pakistan, and Estimation of Risk Assessment

This study investigated the natural incidence of deoxynivalenol (DON) in corn and corn products from corn-producing districts of Punjab, Pakistan. The analysis was carried out using high performance liquid chromatography (HPLC) with UV detector and immunoaffinity cleanup columns. The detection limit (LOD) and limit of quantification were 25 and 50 µg/kg, respectively. A total of 1220 samples of corn and corn products were analyzed to detect DON, and 539 (44.2%) samples were observed to be contaminated with DON (n ≥ LOD). Furthermore, 92 (7.5%) samples of corn and corn products had DON levels that were higher than the proposed limits of the EU. The data are significantly different from a normal distribution of DON in samples of corn and corn products from different locations (p < 0.05) for Shapiro-Wilk and Kolmogorov-Smirnov values. However, a significant difference in DON levels was found between corn and corn-derived products (p ≤ 0.05). The lowest and highest exposures, and hazard quotient (HQ) values of 0.92 and 9.68 µg/kg bw/day, were documented in corn flour samples.

Pathogenetic effects of feed intake containing of fumonisin (Fusarium verticillioides) in early broiler chicks and consequences on weight gain

Fusarium verticillioides is often responsible for contamination of poultry feed with the mycotoxin fumonisin. The objective of the study was to determine whether fumonisin-contaminated feed in the early phase of broiler chicks causes oxidative imbalances and interferes with weight gain. One-day-old male Cobb 500 broiler chicks (n = 80) were divided into four treatments of 20 birds each, all of which were fed basal feed until the 11th day of age. From day 12, some birds were challenged with fumonisin in the feed: Control (T0) continued receiving the basal ration; treatments T1, T2, and T3 were given feed experimentally contaminated with fumonisin at concentrations of 2.5 ppm, 5 ppm and 10 ppm, respectively. After the 5th (day 17) and 10th (day 21) days, ten birds from each treatment were euthanized for blood and tissue collection to measure histopathological, biochemical and oxidative stress markers. All animals were weighed individually at the beginning of the experiment (day 12), and at 17 and 21 days of age. Birds that ingested 10 ppm of fumonisin (T3) had lower (P < 0.05) weight gain compared to those in T0. At 21 days, the body weights of the T1, T2 and T3 chicks were 1.3%, 8.97% and 18.7% lower, respectively, than those of T0. No histological lesions in the livers were observed for any treatment; however, higher levels of reactive oxygen species (ROS: day 21) and lipoperoxidation (LPO: days 17 and 21) were observed, associated with lower liver activity of the enzymes superoxide dismutase (SOD: day 21), glutathione peroxidase (GPx: day 17 and 21) and glutathione S-transferase (GST: day 21) when birds consumed 5 or 10 ppm of fumonisin. In serum, LPO levels and SOD and GPx activities were lower for groups consuming high doses of fumonisin in the diet (T2 and T3); ROS levels and GST activity were higher in these birds. Birds that consumed fumonisin-containing diets had lower levels of alanine aminotransferase, total protein and albumin (T3); as well as lower serum glucose levels (days 17 and 21), uric acid and triglycerides (day 21) in T3 than in T0. At 21 days, there were smaller crypt sizes and intestinal villi in birds that consumed high levels of fumonisin. These results suggest that fumonisin (10 ppm) in chick diet causes hepatic oxidative stress and impairs intestinal health, consequently negatively affecting weight gain.

Mycotoxicological monitoring of breakfast and infant cereals marketed in Brazil

A mycotoxicological survey was conducted in breakfast (n = 172) and infant (n = 43) cereals commercialized in Brazil. Samples were collected in 2018 for analyses of: aflatoxins (AFs) B₁ (AFB₁), B₂, G₁ and G₂; fumonisins (FBs) B₁ (FB₁) and B₂; zearalenone (ZEN); the trichothecenes (TRCs) deoxynivalenol (DON), T-2 toxin, HT-2 toxin, nivalenol, fusarenon X, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol and diacetoxyscirpenol; and ochratoxin A. FB₁ was the most prevalent metabolite in breakfast cereals, being detected in 26.7% of the samples (mean 105 μg/kg); ZEN had the second highest positivity, 14.8% (mean 17 μg/kg), followed by DON with 10% (mean 44 μg/kg). In infant cereals, FB₁ also had the highest incidence, 27.8% (mean 55 μg/kg), followed by DON with 10.3% (mean 36 μg/kg) and ZEN with 6.9% (mean 3 μg/kg). Mycotoxins contamination was found in 31.4% (n = 54) of the breakfast cereals and in 18.6% (n = 8) of the infant cereals. In these positive samples, co-occurrence of two or three mycotoxins was detected in 31.5% (n = 17) of the breakfast cereals and in 25% (n = 2) of the infant cereals. The mycotoxins found co-contaminating the breakfast cereals belong to the genera Aspergillus and Fusarium; ZEN, followed by AFB₁, were the most prevalent ones. As for the infant cereals, the associated fungal metabolites are produced by the genus Fusarium; the highest incidence was seen for ZEN. Low contamination and positivity of mycotoxins were found herein; nonetheless, in some samples these substances were present at levels which transgress those preconized in the Brazilian legislation. Therefore, mycotoxicological monitoring of this type of product throughout the nation is crucial in order to identify the potential risk to which the Brazilian population is exposed, particularly the children.

Fumonisin Production by Fusarium verticillioides in Maize Genotypes Cultivated in Different Environments

Fumonisins are mycotoxins (MTs) produced mainly by the fungus Fusarium verticillioides, the main pathogens of maize which cause ear rot. The aim of this work was to evaluate some factors that may lead to high fumonisin production by F. verticillioides in maize grains, correlating the pathogen inoculation method with different genotypes grown in four Brazilian states. Experiments were conducted in 2015–2016 in maize crops from experimental maize fields located in four distinct states of Brazil. Results showed that contamination by fumonisin mycotoxins occurred even on symptomatic or asymptomatic grains. In all municipalities, the samples showed levels of fumonisin B1 that were higher than would be tolerable for the human consumption of corn products (the current tolerance limit for fumonisin is 1.5 μg g⁻¹). High severity of grains infected with F. verticillioides does not always show high concentrations of fumonisins. Environments with higher temperatures may influence the production of high concentrations of fumonisin in maize hybrids. Spray inoculation methods and inoculation at the center of spikes did not influence fumonisin concentrations. Results showed that the hybrids P3630H, P32R48 and P3250 presented higher disease severity, as well as higher mycotoxin levels in the studied locations with higher temperatures.

Fusarium verticillioides and fumonisin contamination in Bt and non-Bt maize cultivated in Brazil

Fusarium verticillioides is one of the main pathogens of maize, causing ear and stalk rots. This fungus is also able to produce high levels of fumonisins, which have been linked to various illnesses in humans and animals. Previous studies have shown that maize hybrids genetically modified with the cry genes from the bacterium Bacillus thuringiensis (Bt) presented lower incidence of F. verticillioides and fumonisin levels, presumably through the reduction of insects, which could act as vectors of fungi. The aim of this study was to assess the incidence of F. verticillioides and the concentration of fumonisins in Bt and isogenic non-Bt hybrids (2B710Hx, 30F35YG, 2B710, and 30F35, respectively). The samples of 2B710Hx and 30F35YG presented lower F. verticillioides frequency than 2B710 and 30F35 samples. However, there was no statistical difference between fumonisin contamination when Bt and non-Bt samples were compared (P > 0.05). The results suggest that other environmental parameters could possibly trigger fumonisin production during plant development in the field; consequently, other management strategies should be applied to aid controlling fumonisin contamination in maize.

Cooccurrence of mycotoxins in maize and poultry feeds from Brazil by liquid chromatography/tandem mass spectrometry

The objective of this study was to quantitatively evaluate mycotoxins in samples of maize and poultry feed produced in Brazil. A multimycotoxin method based on HPLC-MS/MS was applied to investigate the occurrence of toxical fungal metabolites in 119 samples collected from poultry feed factory integrated poultry farms: maize grain (74), poultry feed (36), and feed factory residue (9). Twenty of 101 fungal metabolites investigated were detected and quantified in the samples: aflatoxins B₁, B₂, G₁, and G₂, fumonisins B₁, B₂, and B₃, hydrolyzed fumonisin B₁, zearalenone, agroclavine, chanoclavine, deoxynivalenol, and nivalenol, and enniatin A, A₁, B, B₁, beauvericin, kojic acid, and moniliformin. Most samples were contaminated with more than one mycotoxin. All samples were contaminated with fumonisins, with medians values of 1,840 μg/kg, 239 μg/kg, and 23,676 μg/kg for maize, feed, and factory residue samples, respectively. Surprisingly, beauvericin was detected in more than 90% of samples. The median contaminations of aflatoxin and trichothecenes were low, near LOD values. The factory residue presented highest contamination levels for all mycotoxins. This is the first study dealing with agroclavine, chanoclavine, enniatin A, A₁, B, B₁, beauvericin, and kojic acid contamination of maize and poultry feeds from Brazil.

Natural occurrence of fumonisins b1 and b2 in corn from three main production provinces in China

A total of 255 corn samples collected in 2010 from three main corn production provinces of China (Liaoning, Shandong, and Henan) were analyzed for contamination with fumonisins (FB(1) and FB(2)). The incidence of contamination was significantly higher in samples from Liaoning than in samples from the other two provinces. Approximately 80.0% of the samples from Liaoning were contaminated with fumonisins, with a mean total fumonisin concentration of 3,990 ng/g. In contrast, the mean total fumonisin concentrations were 845 and 665 ng/g in samples from Shandong and Henan, respectively. The probable daily intake of fumonisins (0.3 μg/kg of body weight) is within the provisional maximum tolerable daily intake of 2.0 μg/kg of body weight set by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives.

Mycotoxicological quality evaluation of corn samples used by processing industries in the Northern region of Paraná State, Brazil

Based on fungal and fumonisin contamination of 870 freshly harvested samples, the quality of corn used by processing industries in the Northern region of Parana State, Brazil (2003 and 2004 crop-year) was evaluated. Sampling was carried out for each crop at two points in the production chain, i.e. at reception by the processors and at the pre-drying step. Corn samples were more frequently contaminated with Fusarium sp. (100%) and Penicillium sp. (84.1-95.3%) than Aspergillus sp. (5.6-19.8%). Fumonisin B(1) (FB(1)) was detected in all samples from the two points in both crop-years. FB(1) levels ranged 0.02-11.83 microg g(-1) in the reception and 0.02-10.98 microg g(-1) in the pre-drying samples of the 2003 crop. Samples from the 2004 crop showed FB(1) levels ranging 0.03-12.04 microg g(-1) in the reception and 0.06-7.74 microg g(-1) in the pre-drying samples. FB(2) levels ranged 0.02-5.25 microg g(-1) in the reception and 0.01-7.89 microg g(-1) in the pre-drying samples (2003 crop-year). In samples from the 2004 crop, FB(2) levels ranged 0.02-6.12 microg g(-1) in the reception and 0.05-3.47 microg g(-1) in the pre-drying samples. Low fumonisin levels were detected in most corn samples used by processors in the Northern region of Parana State, showing a decreasing trend in fumonisin contamination over the years.

Mycoflora and co-occurrence of fumonisins and aflatoxins in freshly harvested corn in different regions of Brazil

Natural mycoflora and co-occurrence of fumonisins (FB₁, FB₂) and aflatoxins (AFB₁, AFB₂, AFG₁ and AFG₂) in freshly harvested corn grain samples from four regions of Brazil were investigated. Fusarium verticillioides was predominant in all samples. Analysis of fumonisins showed that 98% of the samples were contaminated with FB₁ and 74.5% with FB₁ + FB₂, with toxin levels ranging from 0.015 to 9.67 μg/g for FB₁ and from 0.015 to 3.16 μg/g for FB₂. Twenty-one (10.5%) samples were contaminated with AFB₁, seven (3.5%) with AFB₂ and only one (0.5%) with AFG₁ and AFG₂ Co-contamination with aflatoxins and fumonisins was observed in 7% of the samples. The highest contamination of fumonisins and aflatoxins was observed in Nova Odessa (SP) and Várzea Grande (MT), respectively. The lowest contamination of these mycotoxins was found in Várzea Grande and Nova Odessa, respectively.

Effect of the time interval from harvesting to the pre-drying step on natural fumonisin contamination in freshly harvested corn from the State of Parana, Brazil

Natural mycoflora and fumonisins were analysed in 490 samples of freshly harvested corn (Zea mays L.) (2003 and 2004 crops) collected at three points in the producing chain from the Northern region of Parana State, Brazil, and correlated to the time interval between the harvesting and the pre-drying step. The two crops showed a similar profile concerning the fungal frequency, and Fusarium sp. was the prevalent genera (100%) for the sampling sites from both crops. Fumonisins were detected in all samples from the three points of the producing chain (2003 and 2004 crops). The levels ranged from 0.11 to 15.32 microg g(-1)in field samples, from 0.16 to 15.90 microg g(-1)in reception samples, and from 0.02 to 18.78 microg g(-1)in pre-drying samples (2003 crop). Samples from the 2004 crop showed lower contamination and fumonisin levels ranged from 0.07 to 4.78 microg g(-1)in field samples, from 0.03 to 4.09 microg g(-1)in reception samples, and from 0.11 to 11.21 microg g(-1)in pre-drying samples. The mean fumonisin level increased gradually from < or = 5.0 to 19.0 microg g(-1)as the time interval between the harvesting and the pre-drying step increased from 3.22 to 8.89 h (2003 crop). The same profile was observed for samples from the 2004 crop. Fumonisin levels and the time interval (rho = 0.96) showed positive correlation (p < or = 0.05), indicating that delay in the drying process can increase fumonisin levels.

Implication of pre-drying steps with natural fumonisin contamination levels in freshly harvested corn

Maize quality regarding fumonisin contamination of 390 freshly harvested samples used by maize processing industries in the Northern region of Parana State, Brazil (2003 crop) was evaluated and correlated to the time elapsed from harvesting to the pre-drying step. Sampling was carried out at three points of the maize production chain, immediately after harvesting (n=100), at the industry delivery posts (n=200) and before the drying process (n=90). Fumonisin B1 (FB1) was detected in all the samples from the three points of the maize production chain. FB1 levels ranged from 0.11 to 12.68 µg/g (mean 1.81±2.12 µg/g) in the field samples, 0.10 to 11.83 µg/g (mean 1.83±1.75 µg/g) in the reception samples and from 0.02 to 10.98 µg/g (mean 2.31±2.38 µg/g) in the pre-drying samples. FB2 levels ranged from 0.01 to 5.26 µg/g (mean 0.84±0.94 µg/g) in the field samples, from 0.02 to 5.25 µg/g (mean 0.74±0.69 µg/g) in the reception samples and from 0.07 to 7.89 µg/g (mean 1.25±1.29 µg/g) in the pre-drying samples. Although there was no significant difference in mean fumonisin levels among the field, reception and pre-drying samples by the Tukey multiple comparison test (P<0.05), there was a positive correlation (P<0.05) between fumonisin levels and the time elapsed (p=0.95) from harvesting to the pre-drying step. Therefore reduction in the harvest/drying interval would be essential to assure product quality and safety and minimise potential health hazards.

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.

What the primary care pediatrician should know about syndromes associated with exposures to mycotoxins

Disease associated with exposure to mycotoxins is known as the "Great Masquerader" of the 21st century because of its complex natural history involving different tissues and resembling different diseases at each stage in its evolution. It can present with a variety of nonspecific clinical signs and symptoms such as rash, conjunctivitis, epistaxis, apnea, cough, wheezing, nausea, and vomiting. Some cases of vomiting illness, bone marrow failure, acute pulmonary hemorrhage, and recurrent apnea and/or "pneumonia" are associated with exposure to mycotoxins. Familiarity with the symptoms of exposure to the major classes of mycotoxins enables the clinician to ask pertinent questions about possible fungal exposures and to remove the infant or child from the source of exposure, which could be contaminated food(s), clothing and furniture, or the indoor air of the home. Failure to prevent recurrent exposure often results in recurrent illness. A variety of other conditions, including hepatocellular and esophageal cancer and neural tube defects, are associated with consumption of foods contaminated with mycotoxins. Awareness of the short- and long-term consequences of exposures to these natural toxins helps pediatricians to serve as better advocates for children and families.

Human Dietary Exposure to Fumonisin B1 from Iranian Maize Harvested During 1998–2000

Fumonisin B(1) (FB(1)) is the most abundant of the fumonisin mycotoxins, mainly produced in maize by F. verticillioides and F. proliferatum. A previous study on the FB1 contamination of maize harvested in Mazandaran and Isfahan Provinces of Iran in 1998 and 1999 demonstrated contamination in both provinces. This present study was undertaken to further investigate the variation in levels of contamination and to estimate possible levels of human exposure to fumonisins in Iran. The mean level of FB(1) in 49 visually healthy maize samples collected from Mazandaran Province during 2000 was 6.14 mg/kg, which is higher than that found during 1998 and 1999 (2.27 and 3.18 mg/kg, respectively). Although these levels are higher than the Iranian legislative limits for fumonisins in maize intended for humans, the relatively low estimated consumption of maize in Iran (3.3 g/person/day) implies that average exposures (0.011 and 0.215 microg/kg body weight/day in Isfahan and Mazandaran, respectively) are within the provisional maximum tolerable daily intake of 2 microg/kg body weight/day set by the Joint FAO/WHO Expert Committee on Food Additives. Nevertheless, certain sections of the population who may consume higher amounts of maize or who may replace all or some of their consumption of other cereals with maize, could well exceed this limit.

Fumonisins in Brazilian corn-based foods for infant consumption

A survey of 196 samples of corn-based infant foods from 13 cities of Sao Paulo State, Brazil, was carried out to investigate the fumonisin contamination in the products. Based on their ingredients, the products were divided into seven groups: infant cereal designated as types A-D, corn meal, corn starch and instant cereal baby food. Although certain infant food samples were free of fumonisin contamination (<20 microg kg(-1); corn starch and infant cereals of type A, B and D), contamination levels in the other products (corn meal, instant corn-based baby food and cereal type C) were of concern, particularly those in corn meal. All samples in these categories contained fumonisins. The mean level for total fumonisins (FB1 + FB2 + FB3) in corn meal was 2242 microg kg(-1) (maximum 8039 microg kg(-1)), in instant corn-based baby food was 437 (maximum 1096) microg kg(-1) and in infant cereal type C was 664 (maximum 1753) microg kg(-1).

Fumonisin contamination and fusarium incidence in corn from Santa Catarina, Brazil

In Brazil, the southern region has the highest incidence of esophageal cancer and also the highest production and consumption of corn (Zea mays) products. Corn samples intended for human consumption from the western, northern, and southern regions of the state of Santa Catarina, southern Brazil, had mean total fumonisin B (B(1), B(2), and B(3)) levels of 3.2, 3.4, and 1.7 mg/kg, respectively. Fusarium verticillioides, the predominant fungus in the corn samples, had mean incidences (percent of kernels infected) of 14, 11, and 18% for the three regions, respectively. Additional corn samples intended for animal feed from the southern region had a mean total fumonisin level of 1.5 mg/kg and a mean F. verticillioides incidence of 10%. The fumonisin levels in corn from the state of Santa Catarina, Brazil, were similar to the high levels determined in other high esophageal cancer incidence regions of the world.

Improving extraction of fumonisin mycotoxins from Brazilian corn-based infant foods

The current AOAC International methods for the determination of fumonisins have been validated for corn and cornflakes but have produced low recoveries and high variability when applied to processed corn products for infants. Hence, an investigation was undertaken to improve the extraction efficiency for fumonisins by investigating the use of different extraction solvents. Corn-based infant foods containing cornmeal, corn starch, and corn flour were purchased in the city of Campinas, state of Sao Paulo, Brazil, and were analyzed for fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) following extraction with a range of solvents. Comparison of the results from each of the samples indicated that acidified 70% aqueous methanol at pH 4.0 provided the best overall performance, whereas a methanol/boric acid (pH 9.2) mixture displayed poor extraction efficiency. Extraction with acidified 70% aqueous methanol showed seven of eight test samples to be positive for FB1 (range, 30 to 6,127 microg/kg; relative SD, 4.2 to 51.7%), two of eight samples to be positive for FB2 (range, 53 to 1,738 microg/kg; relative SD, 4.5 to 5.3%), and one of eight samples to be positive for FB3 (575 microg/kg). For samples in which extraction with phosphate-buffered mixtures (pH 3) proved superior, the method suffered from poor chromatography due to interfering compounds. The findings indicate that matrix interferences play a significant role in the extractability, cleanup, and chromatography of the fumonisins.

Accumulation of fumonisins B1 and B2 in freshly harvested Brazilian commercial maize at three locations during two nonconsecutive seasons

Fifty-six Brazilian commercial maize cultivars were examined for FB1 and FB2 accumulation after two non-consecutive growing seasons. During the 94/95 growing season 35 cultivars were planted at three locations in the state of São Paulo, Brazil. All samples (total of 105) were contaminated (0.10 micro/g-6.58 microg/g FB1 and 0.04 microg/g-2.15 microg/g FB2). During the 97/98 growing season, 8 of the cultivars used during 94/95 and 21 others were replanted at the same locations. All 87 samples were contaminated (1.15 microg/g-43.80 microg/g FB1 and 0.08 microg/g-11.65 microg/g FB2). One cultivar accumulated significantly less fumonisins in all locations during both growing seasons, indicating that some degree of selection may be possible even in climates that favor F. moniliforme (verticillioides) infection of maize. The presence of water surplus in soil from kernel maturity to harvest correlated with concentrations of FB1 in the grain for the 8 cultivars planted during both seasons at three locations. Observed trends indicated that water excesses and deficits from silking to harvest increased fumonisin levels. The difference in the incidence of FB1, FB2, and FB1 + FB2 was significant between growing seasons, planting locations and between cultivars. Neither the level of hybridization, nor the type of endosperm, nor the length of the vegetative cycle showed any effect on the FB1 contamination.

New Amylase Inhibitor Present in Corn Seeds Active In Vitro Against Amylase from Fusarium verticillioides

A screening for specific amylase inhibitor levels against amylase from Fusarium verticillioides (Fusarium moniliforme), the most relevant mycotoxigenic fungus in corn, was conducted on 37 corn hybrids. The amylase inhibitor levels in these hybrids ranged from 5.5 to 16.0 amylase inhibitor units per gram of corn (AIU/g) in the MASTER and AG5011 hybrids, respectively. The hybrid with the maximum content of inhibitor was used as the source of this new protein. The inhibitor was partially purified using fractional precipitation, gel filtration on Sephadex G-75 column, high performance liquid chromatography (HPLC) Superose HR 10/30 column, and HPLC anion exchange chromatography, obtaining a 20.7-fold purification. Electrophoresis after denaturing and heating under reductive conditions showed an apparent 23.8 kDa molecular mass and an acidic isoelectric point of 5.4, which differs from previous molecular masses reported for other inhibitors present in corn seeds (14 and 22 kDa). This inhibitor showed activity against amylases from human saliva and pancreas, from the fungi F. verticillioides and Aspergillus flavus, and from the insects Acanthoscelides obtectus, Zabrotes subfasciatus, Tribolium castaneum, and Sitotroga cerealella. The mycoflora found in the corn grain indicated Fusarium sp. as the most prevalent fungi (81.1% of the samples), with a count ranging from 1.5 × 10² to 2.4 × 10⁶ CFU/g of corn. The presence of fumonisins was detected in 21 out of the 37 hybrids studied, ranging from 0.05 to 2.67 μg of FB per gram of corn. No correlation could be established between this amylase inhibitor level in the corn seeds and the presence of Fusarium sp. or with the fumonisin content under the experimental conditions of the test.

Post-harvest storage of corn: effect of beginning moisture content on mycoflora and fumonisin contamination

The effect of storage on mycoflora profile was monitored bimonthly in 36 corn (Zea mays L.) samples, dividing the same sample into groups dried to 11 and 14% moisture content (1008 analysis). These groups were further subdivided based on the initial total count (moulds and yeasts) up to 10(4) CFU g(-1) (12 samples, range 1.6 x 10(4) to 9.0 x 10(4), mean 3.8 x 10(4) CFU g(-1)) and up to 10(5) CFU g(-1) (24 samples, range 1.0 x 10(5) to 5.0 x 10(5), mean 2.7 x 10(5) CFU g(-1)). In the corn group dried to 11%, the fumonisin content was analysed at the initial stage (freshly harvested) and at the end of 12-month storage. Fusarium spp. and Penicillium spp. prevailed at the freshly harvested stage (100%), maintaining this profile throughout 12 months, in corn dried to both 11 and 14%. Cladosporium spp., Aspergillus spp. and Phoma spp. were also detected at lower frequencies during the storage. Fusarium spp. and the total fungal colony count during 12-month storage carried out with samples dried to 11 or 14% moisture content were statistically evaluated using ANOVA for randomized complete block design. The correlation between storage time and Fusarium spp. and total fungal colony count data was analysed by Pearson's correlation test. There was no difference in Fusarium spp. and total counts in the 10(4) CFU g(-1) initial total count group throughout the storage time (p < 0.05). There was a negative correlation between fungal population and storage time (p < 0.05) in the 10(5) CFU g(-1) initial total count group. Fumonisins were detected in all freshly harvested corn, at a mean concentration of 9.9 +/- 6.0 micro g g(-1) (range 0.74-22.6 micro g g(-)1). These values did not change in the 12-month stored corn (mean of 9.9 +/- 5.8 micro g g(-1), range 0.81-23.7 micro g g(-1)). These post harvest data indicated the importance of moisture content at the crop harvesting/predrying stage to control fungal growth and further fumonisin production.

Mycoflora and fumonisin contamination in Brazilian corn from sowing to harvest

The present study aimed to analyze the mycoflora and potential mycotoxin contamination of soil and corn samples collected at different plant maturity stages in Capão Bonito and Ribeirão Preto, two regions of the State of São Paulo, Brazil. In addition, the data obtained were correlated with the occurrence of wind-dispersed fungi and the predominant climatic conditions of the two regions studied. Corn mycoflora profiles showed that Fusarium verticillioides prevailed in 35% of the samples from Capão Bonito and in 49% of the samples from Ribeirão Preto. Examination of wind-dispersed fungi also revealed a high incidence of F. verticillioides. Soil mycoflora analyses showed that Penicilliumwas the most prevalent genus, although F. verticillioides was present in 55.5% of Capão Bonito's samples and in 26.7% of Ribeirão Preto's samples. With respect to water activity, the corn kernels most contaminated with F. verticillioides had water activity levels of 0.70-0.80. HPLC analysis of fumonisins revealed that 88.5% of Capão Bonito's kernels were contaminated with fumonisin B(1) (FB(1)) (0.09-10.87 microg/g) and 53.8% with fumonisin B(2) (FB(2)) (0.05-0.52 microg/g); Ribeirão Preto's kernels presented contamination levels of 93.5% for FB(1) (0.11-17.69 microg/g) and 61.3% for FB(2) (0.05-5.24 microg/g). No aflatoxins were detected by thin-layer chromatography in corn grains of either region. The concomitant occurrence of F. verticillioides and fumonisins in most of the field corn assayed demonstrates the importance of an effective control of cultivation throughout the plant maturity stages.

Immunohistochemistry of fumonisin in poultry using avidin-biotin-peroxidase system

Using monoclonal anti-fumonisin B1 antibody (anti-FB1) and avidin-biotin-peroxidase system, liver and kidneys of broiler chicks were evaluated for the detection and distribution of fumonisins (FBs). One hundred and fifty micrograms of FB1 or culture extract of Fusarium moniliforme str. 113F containing 150 microg of FB1 and 4 microg of FB2 were administered into the vitelline sac of 1-day old, specific pathogen-free chicks. The animals were killed 24 h after injection, and renal and hepatic tissues submitted for immunohistochemical analysis. FBs were detected in the epithelial cells of convoluted distal and proximal tubules of the kidneys, as well as in the cytoplasm of hepatocytes. This novel immunohistochemical method developed is expected to be an efficient way for monitoring the target of the FB toxins in tissues.

Co-occurrence of aflatoxins B1, B2, G1, G2, zearalenone and fumonisin B1 in Brazilian corn

Two hundred and fourteen unprocessed corn samples (1997-98 harvest), collected at wholesale markets in different regions in Brazil, were surveyed for the occurrence of mycotoxins. The samples were analysed for aflatoxins B1, B2, G1, G2, zearalenone and fumonisin B1 using in-house validated methods. The occurrence of aflatoxin B1, zearalenone and fumonisin B1 was found in 38.3, 30.4 and 99.1% of the samples, respectively. Aflatoxin B1, zearalenone and fumonisin B1 contamination levels varied from 0.2 to 129, 36.8 to 719, and 200 to 6100 microg/kg, respectively. The co-occurrence of the two carcinogenic mycotoxins aflatoxin B1 and fumonisin B1 was observed in 100% of the aflatoxin-contaminated samples (82 samples). Co-occurrences of aflatoxin B1: zearalenone: fumonisin B1 and aflatoxin B1: aflatoxin B2: fumonisin B1 were found in 18 and 43 samples, respectively.

Evaluation of fumonisin-aflatoxin co-occurrence in Brazilian corn hybrids by ELISA

The natural co-occurrence of fumonisins and aflatoxins was investigated in freshly harvested corn kernels (150 samples, 62 hybrids), acquired from the Central-Southern (27 samples, 21 hybrids), Central-Western (86 samples, 51 hybrids) and Northern (37 samples, 18 hybrids) regions of the State of Paraná, Brazil using enzyme-linked immunosorbent assay (ELISA). Fumonisins were detected in 147 (98%) samples at a concentration range of 0.096 to 22.6 microg/g, while aflatoxins were detected in 17 (11.3%). All the aflatoxin-positive samples (range 38.0-460.0 ng/g) came from the Central-Western region and were co-contaminated with fumonisins. Fumonisin contamination was higher in corn from the Northern (9.85 microg/g) and Central-Western regions (5.08 microg/g), when compared with the Central-Southern region (1.14 microg/g). The overall evaluation detected 62% samples with fumonisin levels < or = 5.0 microg/g. Regional differences affected fumonisin levels in the same hybrid, regardless of Fusarium count and moisture content, suggesting interference from climatic conditions, in addition to the local predominance of toxigenic strains of the Fusarium biotype.

Identification of deoxynivalenol, 3-acetyldeoxynivalenol and zearalenone in the galactose oxidase-producing fungus Dactylium dendroides

The galactose oxidase-producing fungus Dactylium dendroides was re-identified as a Fusarium species. Fungi of this genus are well known for the production of mycotoxins. Verification of growth of this fungus on rice, corn and liquid medium described for the production of galactose oxidase is provided to determine whether the fungus could produce Fusarium toxins, namely, moniliformin, fusaric acid, fumonisin, zearalenone and the trichothecenes, deoxynivalenol, 3-acetyldeoxynivalenol, fusarenone, nivalenol, diacetoxyscirpenol, neosolaniol, and toxin T-2. Under the culture conditions used, deoxynivalenol, 3-acetyldeoxynivalenol and zearalenone were detected in the fungal culture medium. The finding is consistent with the hypothesis that the fungus is in fact a Fusarium species.

Effect of climatic conditions on natural mycoflora and fumonisins in freshly harvested corn of the State of Paraná, Brazil

Natural mycoflora associated with fumonisins were analyzed in 150 samples of freshly harvested corn from Central-Southern, Central-Western and Northern regions of the State of Paraná, Brazil and correlated to climatic conditions. The corn samples were frequently contaminated with Fusarium sp. (98.7 to 100%) and Penicillium sp. (93 to 100%), when compared to Aspergillus sp. (not detected to 27.7%). The highest contamination with potentially mycotoxigenic fungi occurred in corn harvested in the Central-Western region, where total mould and yeast counts ranged from 5.5 x 10(3) to 5.2 x 10(6) CFU/g, with 98.7% contaminated by Fusarium sp. and 93% by Penicillium sp. In this region F. moniliforme (F. verticillioides) was the predominant Fusarium sp., and was isolated in 85.9% of the samples. Aspergillus sp. was isolated from 27.7% samples. FB1 was detected in 100% of the samples (mean of 2.39 micrograms/g) and FB2 in 97.7% (mean of 1.09 micrograms/g). Fumonisins were also detected in all samples from Northern region, with mean of 4.56 micrograms/g (FB1) and 2.20 micrograms/g (FB2). Considering 1.0 microgram/g as the threshold, 72% of the corn samples from the Central-West and 92% from the North were contaminated with concentrations above this value, in contrast to a 18.5% contamination rate from Central-Southern samples. Between corn planting to harvesting season, the average maximum temperature and relative humidity were 26 degrees C and 77.1% (Central-Southern), 27 degrees C and 69% (Northern) and 29.9 degrees C and 89.1% (Central-Western). Therefore, the higher fumonisins contamination of corn from Northern region when compared to the Central-South were due to the differences in rainfall levels (92.8 mm in Central-Southern, 202 mm in Northern) during the month preceding harvest.

Fumonisins B1 and B2 in Brazilian corn-based food products

Eighty-one samples of corn products were acquired from markets and supermarkets in the city of Campinas, SP, Brazil, and were analysed for fumonsins B1 and B2 (FB1 and FB2). Forty samples (49%) were positive for FB1 (0.03-4.93 (micrograms/g) and 44 samples (54%) for FB2 (0.02-1.38 (micrograms/g). The samples, in order of decreasing contamination, were, corn meal (all contaminated, 0.56-4.93 (micrograms/g FB1), followed by degerminated corn (8/11 samples, nd-4.52 (micrograms/g FB1), corn flour (9/11 samples, nd-1.46 (micrograms/g FB1), precooked corn flour (4/6 samples, nd-1.79 (micrograms/g FB1), corn grits (2/2 samples, 0.17-1.23 (micrograms/g FB1), and popcorn (4/9 samples, nd-1.72 (micrograms/g FB1). Relatively lower incidences and levels of contamination were found in corn flakes (1/4 samples, nd-0.66 (microgram/g FB1) and corn flour baby cereal (1/2 samples, nd and 0.44 (microgram/g FB1). The samples of corn on the cob (common corn in the milky stage, 7 samples) and of the typical foods 'curau' (2 samples) and 'pamonha' (7 samples), both prepared with corn in the milky stage, did not show any detectable contamination. Canned sweet corn, also harvested in the milky stage, exhibited a very low incidence of and level of contamination (2/11 samples, nd-0.08 (microgram/g FB1). The intake of corn products is low in urban areas and in most rural areas in Brazil. In certain rural areas, however, corn products play a greater role in daily meals and the calculated intake of FB1 is higher than a proposed Tolerable Daily Intake of 800 ng/kg bw/day. This is the first report on fumonisins in Brazilian corn-based food products.

Natural occurrence of fumonisins B(1) and B(2) in domestic maize of Taiwan

Samples of maize grown in various districts of Taiwan were collected and analyzed for the presence of fumonisin B(1) (FB(1)) and fumonisin B(2) (FB(2)) using high-performance liquid chromatography. Forty-nine (44.5%) and 2 (1.8%) of 110 samples were found to contain FB(1) (109-1148 ng/g) and FB(2) (222-255 ng/g), respectively. The frequency of detection and also the maximum FB(1) concentration were found in samples from Penton (2/2, 262 ng/g), followed by Chiayi (18/26, 264 ng/g), Tainan (8/16, 160 ng/g), Hualinen (5/14, 1148 ng/g), Taitung (7/20, 109 ng/g), and Yunlin (9/26, 361 ng/g). Of the 110 samples examined, only 2 samples from Hualinen had been detected containing FB(2). During an analysis of the distribution pattern of FB(1), it became apparent that >79% of tested samples had FB(1) concentrations <100 ng/g, whereas 2.7% (or 3 samples) contained FB(1) >300 ng/g. These results clearly illustrated that domestically produced maize for human consumption is frequently contaminated with FB(1).

Fumonisins as a possible contributory risk factor for primary liver cancer: a 3-year study of corn harvested in Haimen, China, by HPLC and ELISA

Employing HPLC fluorometry, gas-liquid chromatography (GLC) and a novel enzyme-linked immunosorbent assay (ELISA) based on a monoclonal antibody, 40 corn samples, each collected in 1993 from agricultural stocks for human consumption in Haimen (Jiangsu County) and Penlai (Shandong Province), high- and low-risk areas for primary liver cancer (PLC) in China, respectively, were analysed for fumonisins (FBs), aflatoxins (AFs) and trichothecenes. Levels and positive rates of FBs and deoxynivalenol (DON) were significantly higher in Haimen than in Penlai. ELISA of the 40 corn samples harvested in the two areas in 1994 revealed that FB contamination levels and rates in these areas were comparable to those observed in 1993 in Haimen. ELISA analysis of 1993 and 1994 products revealed a wide occurrence of AFB1 but the positive rates as well as levels were not significantly different between these areas. ELISA of the same sample number of corn harvested in 1995 revealed that FB contamination in Haimen was significantly higher than in Penlai. These 3-yearly surveys of corn samples (240 in total) demonstrated that corn harvested in Haimen was highly contaminated with FBs and that the contamination level, as well as positive rate in 1993 and 1995, were 10-50-fold higher than those in Penlai, suggesting FBs as a risk factor for promotion of PLC in endemic areas, along with the trichothecene DON. Co-contamination with AFs, potent hepatocarcinogens, was assumed to play an important role in the initiation of hepatocarcinogenesis.