Mycotoxin contamination of maize hybrids after infection with Fusarium proliferatum

The ear rot severity of nine maize hybrids and the accumulation of fumonisin B₁(FB₁), fumonisin B₂(FB₂), beauvericin (BEA) and fusaproliferin (FP) after artificial inoculation in the field with a toxigenic strain of Fusarium proliferatum have been investigated. Different degrees of ear rot were observed in different hybrids. Inoculated ears contained 11–38% of Fusarium-damaged kernels (FDK). Mycotoxin analyses showed a pronounced contamination of FDK with concentrations ranging from 116 to 343 mg kg⁻¹ for FB₁, from 8 to 29 mg kg⁻¹ for FB₂, from 1 to 14 mg kg⁻¹ for BEA and from 2 to 10 mg kg⁻¹ for FP. Lower levels of contamination were found in healthy-looking kernels (up to 26, 2, 0.2 and 0.3 mg kg⁻¹ for FB₁, FB₂, BEA and FP respectively). A good correlation was observed between mycotoxin contamination and the Fusarium ear rot index, calculated on the basis of average ear infection with a scale ranging from 0 to 500 to represent healthy cobs and totally rotted cobs respectively. © 1999 Society of Chemical Industry     

Management of fumonisin contamination in maize kernels through the timing of insecticide application against the European corn borer Ostrinia nubilalis Hübner

The European corn borer (ECB), Ostrinia nubilalis, is the principal pest of maize in Central and South Europe. It is known to promote Fusarium verticillioides infection in maize grain, a recognized producer of fumonisins. Field experiments were performed in 2006 and 2007 in two sites in NW Italy to determine the effects of the timing of insecticide application on ECB damage, fungal ear rot and fumonisin contamination under natural conditions. Different insecticide application timings were compared, from maize flowering to approximately 15 days after the flight peak of adult ECB. At harvest, the ears were rated for incidence and severity of ECB damage, fungal ear rot symptoms and fumonisin (FB₁ + FB₂) contamination. In all years/sites, treatments applied at the beginning of consistent ECB flight activity were most effective in controlling insect damage on ears. Fungal ear rot and fumonisin contamination were significantly affected by ECB control. The efficacy of the best timing of insecticide application in controlling fumonisin contamination was, on average, 93% compared to the untreated control. Contamination levels of these mycotoxins increased with either an earlier or later treatment. Furthermore, an earlier insecticide application showed lower fumonisin contamination than a treatment applied after the adult flight peak. Production of maize kernels and maize-based foods that do not exceed the maximum international and EU permitted levels for fumonisins could be enhanced by appropriate insecticide treatment against second generation ECB. The optimum time for insecticide application is between the beginning of consistent adult flight activity and the flight peak.     

On fumonisin incidence in monoculture maize under no‐till,conventional tillage and two nitrogen fertilisation levels

BACKGROUND: Fusarium ear rot and fumonisin contamination are serious problems for maize growers. The lack of maize genotypes highly resistant to fumonisin contamination emphasises the need for management strategies to prevent contamination by this mycotoxin. There are conflicting reports regarding no‐till and nitrogen (N) fertilisation practices in relation to the incidence of fumonisins. In this study the effect of no‐till compared with conventional tillage and of N fertilisation rates on fumonisin occurrence was investigated over three years in Northern Italy. RESULTS: The average contamination of grain by fumonisins B₁ and B₂ over the three years was significantly different, with a lower value in 2000 (516 µg kg^?1) than in the other years (5846 and 3269 µg kg^?1 in 2001 and 2002 respectively). Conventional tillage and no‐till treatments had no significant effect on the incidence of fumonisins. This finding suggests that above‐ground residues infected by Fusarium would not lead to an increase in fumonisin incidence. However, N fertilisation significantly increased fumonisin levels, by 99 and 70% in 2000 and 2001 respectively. CONCLUSION: Maize monoculture does not show a cumulative effect on the occurrence of fumonisins, while high rates of N fertiliser consistently result in elevated fumonisin levels. Both these effects can be influenced by annual meteorological fluctuations. Copyright © 2008 Society of Chemical Industry     

Investigations on Fusarium spp. and their mycotoxins causing Fusarium ear rot of maize in Kosovo

After wheat, maize (Zea mays L.) is the second most important cereal crop in Kosovo and a major component of animal feed. The purpose of this study was to analyse the incidence and identity of the Fusarium species isolated from naturally infected maize kernels in Kosovo in 2009 and 2010, as well as the mycotoxin contamination. The disease incidence of Fusarium ear rot (from 0.7% to 40% diseased ears) on maize in Kosovo is high. The most frequently Fusarium spp. identified on maize kernels were Fusarium subglutinans, F. verticillioides/F. proliferatum and F. graminearum. Maize kernel samples were analysed by LC-MS/MS and found to be contaminated with deoxynivalenol (DON), DON-3-glucoside, 3-acetyl-DON, 15-acetyl-DON, zearalenone, zearalenone-14-sulphate, moniliformin, fumonisin B₁ and fumonisin B₂. This is the first report on the incidence and identification of Fusarium species isolated from naturally infected maize as well as the mycotoxin contamination in Kosovo.     

Timing clorpirifos + cypermethrin and indoxacarb applications to control European corn borer damage and fumonisin contamination in maize kernels

BACKGROUND: European corn borer (ECB) is the main maize pest in central and southern Europe and it promotes the infection of maize with Fusarium verticillioides, which is able to produce fumonisins. Field experiments were performed from 2006 to 2007 in northwestern Italy to determine the effects of the timing of insecticide applications on maize fungal ear rot and fumonisin contamination in natural infection conditions. Four application timings and two insecticides (clorpirifos + cypermethrin and indoxacarb) were compared each year. RESULTS: In both years, the treatments applied at the beginning of a consistent ECB flight activity and at the flight peak showed the best efficacy to control the insect damage on ears. Fungal ear rot and fumonisin contamination were clearly affected by ECB control. The efficacy of the best application timing to control fumonisin occurrence was 73% in 2006 and 84% in 2007. Earlier insecticide applications showed lower fumonisin contamination than treatments applied after the adult flight peak. CONCLUSION: The production of maize and maize‐based foods with a low fumonisin content may be enhanced through correct insecticide application against the second ECB generation. The optimum timing of insecticides is between the beginning of a consistent adult flight activity and the flight peak. Copyright © 2009 Society of Chemical Industry     

Aflatoxin B1 and total fumonisin contamination and their producing fungi in fresh and stored sorghum grain in East Hararghe,Ethiopia

Natural contamination of sorghum grains by aflatoxin B₁ and total fumonisin and their producing toxigenic fungi has been studied. A total of 90 sorghum grain samples were collected from small-scale farmers’ threshing floors and 5–6 months later from underground pits during 2013 harvest from three districts of East Hararghe, Ethiopia. Mycotoxin analysis was done using enzyme-linked immunosorbent assay (ELISA). The limits of detection were in the range 0.01–0.03 μg kg^–1. The results revealed that all sorghum grain samples were contaminated with both Aspergillus and Fusarium species. Aflatoxin B₁ was detected at levels ranging from ?1 grain. There were marked variations in aflatoxin B₁ concentrations between fresh and stored samples, with much higher levels in the latter. Total fumonisin levels varied between 907 and 2041 µg kg^?1 grain across the samples. Lowest total fumonisin was recorded in freshly harvested sorghum grain samples. Sorghum is a main staple cereal in the studied districts and its consumption per day per person is high. Daily intake of low doses of mycotoxin-contaminated food stuff over a period of time could lead to chronic mycotoxicosis.     

Analysis of potential fumonisin‐producing Fusarium species in corn products from three main maize‐producing areas in eastern China

BACKGROUND: Fusarium species are common fungal contaminants of maize and a number of them can produce mycotoxin fumonisins. China is one of the largest maize producers in the world. This study investigated the contamination of maize samples from three areas in eastern China by Fusarium and fumonisin‐producing fungi as well as their fumonisin‐producing potential. RESULTS: A total of 22 Fusarium strains were isolated, 19 of which were able to produce fumonisin. Among the 19 strains, 16 belonged to F. verticillioides, two to F. subglutinans and one to F. proliferatum. The majority (17/19) of the fumonisin‐forming strains were high FB₁ producers, which is a potential health risk for the population in these areas. Fusarium contamination in samples from the mideastern area was the most serious (11 Fusarium strains, with nine producing fumonisin, isolated from 24 samples), followed by the northeastern area (nine Fusarium strains, with all nine producing fumonisin, isolated from 21 samples) and the southeastern area (two Fusarium strains, with one producing fumonisin, isolated from 19 samples). CONCLUSION: Although the overall levels of FBs and contamination by fumonisin‐producing fungi in corn samples were not serious, the contaminating Fusarium strains possessed fairly strong toxicogenic ability and potential risk for food safety. © 2012 Society of Chemical Industry     

Relative severity of fumonisin contamination of cereal crops in West Africa

Traditional and improved varieties of maize, pearl millet and sorghum were planted by small-scale farmers under the direction of the International Institute for Tropical Agriculture in two Nigerian agro-ecological zones: the Sudan Savanna and the Northern Guinea Savanna. Samples were collected for the determination of Fusarium infection and fumonisin (B₁, B₂ and B₃) contamination. A previous paper reported Aspergillus infection and aflatoxin contamination of these samples. Fusarium infection levels, measured by per cent kernels infected, were modest with mean levels for the above cereals of 16% ± 11% (SD), 12% ± 7% and 13% ± 16%, respectively. However, the Fusarium species recovered from maize were predominantly the fumonisin producers F. verticillioides and F. proliferatum, together making an infection rate of 15% ± 10%, whereas these species were present to a limited extent only in the other two cereals, 1% ± 1% for pearl millet and 2% ± 6% for sorghum. Fumonisin contamination was variable but reflected the diversity of Fusarium producers in these three cereals. Mean levels were 228 ± 579 µg kg^–1 (range < 5–2860 µg kg^–1) for maize, 18 ± 7 µg kg^–1 (range = 6–29 µg kg^–1) for pearl millet and 131 ± 270 µg kg^–1 (range < 5–1340 µg kg^–1) for sorghum. Together with previous results on aflatoxin, this study confirmed the co-occurrence of aflatoxins and fumonisins in maize as well as in the traditional African cereals, millet and sorghum (89% co-occurrence across all three cereals). The low fumonisin levels may be ascribed to the use of good agricultural practices. Of the Fusarium species present, those in maize consisted mainly of fumonisin producers, the opposite of what was observed in pearl millet and sorghum. It is concluded that replacement of maize by pearl millet and sorghum could improve food safety with regards to aflatoxin B and fumonisin B exposure.     

Incidence of Fusarium verticillioides and levels of fumonisin B1 and B2 in corn in Turkey

A total of 100 corn samples conforming collected from local farmers and markets from districts of Samsun, Turkey, were analyzed for Fusarium verticillioides, fumonisin B₁ and B₂ contamination. Ninety-three corn samples were found to contain F. verticillioides, 52 samples fumonisin B₁, and 25 samples fumonisin B₂. Fumonisin B₁ contamination ranged from 0.05 to 25.72 mg/kg and B₂ from 0.05 to 5.7 mg/kg, respectively. This figure indicated widespread contamination of fumonisin B₁ and B₂ in maize grown in different areas of Samsun, Turkey.     

Fungal and bacterial metabolites associated with natural contamination of locally processed rice (Oryza sativa L.) in Nigeria

This study reports the fungal and bacterial metabolites associated with natural contamination of 38 composite samples of locally processed rice from five agro-ecological zones of Nigeria (AEZs). The samples were evaluated for the presence of microbial metabolites by LC-MS/MS. Among the identified metabolites, 63 fungal and 5 bacterial metabolites were measured at varying concentrations and occurrence levels. Fusarium toxins had the highest incidence of 79%, but occurred in low amounts with fumonisin B₁ (FB₁) having the highest percentage incidence of 39.5% and a mean of 18.5 µg/kg. Among the Aspergillus toxins, aflatoxins (AFs) occurred in 36.9% of the rice samples, with aflatoxin B₁ (AFB₁) having the highest occurrence level of 18.4% and a mean value of 5 µg/kg. About 12 metabolites had incidence levels > 50%, including beauvericin (BEA) and tryptophol, which had occurrence levels of 100%. Among the emerging toxins under evaluation by international organisations such as the European Food Safety Authority (EFSA) and the Food and Agriculture Organisation of the United Nations (FAO), citrinin, sterigmatocystin (STER) and beauvericin were detected with maximum values of 207, 125 and 131 μg/kg, respectively. This paper also reports the first documented evidence of the contamination of Nigerian rice by bacterial and Alternaria metabolites, nivalenol, kojic acid, STER, moniliformin, fusaric acid, fumonisin B₃, citrinin, 3-nitropropionic acid, andrastin A, cytochalasins, emodin and physicon.     

Factors associated with fumonisin contamination of maize in Uganda

BACKGROUND: During production and handling, maize is attacked by many Fusarium species, some of which are prolific producers of fumonisins. Contamination of maize with fumonisins is influenced by climate, agronomic and postharvest practices. This study investigated the factors associated with the occurrence of fumonisins in maize produced in three agroecological zones of Uganda. RESULTS: All the maize samples were positive for fumonisins with levels ranging from 0.27 to 10 mg kg^?1. A positive and significant correlation (P < 0.01) was observed between fumonisin levels and agroecological zone. Maize from high altitude zone had significantly higher (P < 0.05) mean total fumonisin content (4.93 mg kg^?1) than maize from the mid altitude‐moist (4.53 mg kg^?1) and mid altitude‐dry (4.50 mg kg^?1) zones. Five farmer practices, namely intercropping, crop rotation, delayed harvesting, drying maize on bare ground and planting treated seeds were significantly associated with fumonisin production in maize. Intercropping, delayed harvesting and drying maize on bare ground increased fumonisin contamination whereas crop rotation and planting treated seeds reduced the contamination. CONCLUSION: All maize samples obtained from the three agroecological zones were contaminated with fumonisins. The study showed that some of the farmers' practices predispose maize to fumonisin contamination. The findings are important for future studies aimed at designing strategies to control and prevent contamination of maize with fumonisins. Copyright © 2009 Society of Chemical Industry     

The Contamination of Kenyan Lager Beers with Fusarium Mycotoxins

Seventy five samples of two popular lager beers, namely Pilsner and Tusker were randomly collected from the city of Nairobi and the surrounding satellite towns in Kenya. The samples were analyzed for the presence of 4 mycotoxins, namely, deoxynivalenol (DON), fumonisin B₁ (FB₁), zearalenone (ZEA), and aflatoxin B₁ (AFB₁), by the competitive enzyme linked immunosorbent assay (ELISA) technique. The incidences of DON and ZEA were 100% in both brands, while for FB₁ the incidence was 72%, with incidences in Tusker (76.9%) being significantly higher than in Pilsner (66.7%) (p = 0.00). The mean values for contamination were 3.29 and 3.57 ng/mL for DON, 0.28 and 0.32 ng/mL for FB₁ and 7.84 and 8.50 pg/ml for ZEA in Tusker and Pilsner brands respectively. A positive occurrence association was found between DON and FB₁ and DON and ZEA, an indication of their common source from Fusarium sp. The results suggest low levels and safe exposure to consumers of Kenyan lager beers with Fusarium mycotoxins.     

Contamination of barley seeds with Fusarium species and their toxins in Spain: an integrated approach

Fusarium is a globally distributed fungal genus that includes different species pathogenic to cereals among others crops. Some of these Fusarium species can also produce toxic compounds towards animals and humans. In this work, the presence of the most important Fusarium toxins was determined in barley seeds from Spain, sampled according to European Union requirements. The results obtained were compared with the presence of mycotoxigenic species considered responsible for their synthesis by using species-specific polymerase chain reaction protocols. Fumonisins B₁ and B₂, zearalenone, trichothecenes type A (T-2 and HT-2) and trichothecenes type B (deoxynivalenol and nivalenol) were analysed by using high-performance liquid chromatography. Deoxynivalenol and zearalenone were detected in 72% and 38% of the barley samples, respectively, at levels below European Union limits in all cases. However, the co-occurrence of both toxins in 34% of the samples suggested that synergistic activity of these two mycotoxins should be evaluated. Nivalenol and HT-2/T-2 were detected at low levels in 17% and 10% of the samples, respectively. Fumonisins occurred in 34% of the samples at levels up to 300?µg/kg. This suggested that they might represent a risk in Spanish barley, and to our knowledge, this is the first report on the presence of fumonisins in barley in this country. The species-specific polymerase chain reaction assays to detect mycotoxin-producing Fusarium species showed a very consistent correlation between F. verticillioides detection and fumonisin contamination as well as F. graminearum presence and zearalenone, deoxynivalenol and nivalenol contamination in barley samples. The approach used in this study provided information of mycotoxin contamination of barley together with the identification of the fungal species responsible for their production. Detection of the species with the current polymerase chain reaction assay strategy may be considered predictive of the potential mycotoxin risk in this matrix.     

Fumonisin B1 and B2 occurrence in dried fig fruits (Ficus carica L.) under Meander Valley's climatic conditions and relationship with fruit quality

Fusarium is the agent causing endosepsis (internal rot) in fig fruits and it is widespread in fig orchards in the Aegean region. This research was conducted to determine the natural occurrence of fumonisin B₁ (FB₁) and B₂ (FB₂) on dried fig fruits of Sarilop (syn. Calimyrna) variety which are mainly grown in the Big and Small Meander Basins in the Aegean region, representing 60% of world dried fig production. A total of 262 samples belonging to two quality classes, Class A and Class cull, were collected from 12 different locations during the two crop years in 2004 and 2005. The fumonisin detection method is based on extraction with methanol–acetonitrile–water, derivatization with o-phthaldehyde and quantification by reversed-phase high-performance liquid chromatography with fluorescence detection. The mean concentrations of FB₁ and FB₂ in fumonisin-positive samples were 0.080?±?0.047?µg?g^?1 and 0.055?±?0.031?µg?g^?1 and ranged from LOD to 0.332?µg?g^?1 and from LOD to 0.198?µg?g^?1, respectively. The incidence of fumonisins significantly differed between the two crop years. This difference can be attributed to the alteration in the rainfall regime from mid-May to mid-August (7.2?mm in 2004, 90.9?mm in 2005) and number of humid wind currents from a westerly direction (183 in 2004, 492 in 2005) from the end of July and mid-August that may have triggered a higher incidence of Fusarium spp. and thus fumonisin production.     

Mycoflora and natural occurrence of aflatoxin,cyclopiazonic acid,fumonisin and ochratoxin A in dried figs

Mycoflora, the mycotoxigenic properties of moulds, and natural contamination with mycotoxins such as aflatoxins (AFs), cyclopiazonic acid (CPA), fumonisin B₁ (FB₁) and ochratoxin A (OTA) were investigated in dried figs. Dry fig samples were collected from orchards during the drying stage in the Aegean Region of Turkey. Fungal isolates were identified using morphological, chemical as well as molecular methods. Mycotoxigenic characteristics of moulds were assessed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Mycotoxins except CPA (by TLC) were determined by HPLC. All the fig samples were contaminated with moulds and 94.7% contained one or more mycotoxigenic species. The most prevalent moulds present in dried figs belong to the Aspergillus section Nigri members, being 93.9% positive for the samples, followed by Fusarium spp., Aspergillus section Flavi and Penicillium spp. On the other hand, Fusarium spp. had the highest count and the number of fumonisin producing Fusarium was also high. A total of 48% of 115 dried fig samples contained OTA (range?=?0.1–15.3?ng?g^?1), 74.7% of the samples had FB₁ (range?=?0.05–3.65?mg?kg^?1), 10.0% of the samples had aflatoxin (range?=?0.1–763.2?ng?g^?1) and 24.3% of the samples were tentatively identified as being contaminated with CPA (range?=?25–187?ng?g^?1). Dried fig samples were contaminated with one (33.0%), two (47.0%), three (5.2%) and four mycotoxins (3.5%). A total of 11.3% of dried fig samples were not contaminated with any of the four mycotoxins. To the best of our knowledge, CPA and fumonisin have been found for the first time in dried figs.     

Identification,mycotoxin risk and pathogenicity of Fusarium species associated with fig endosepsis in Apulia,Italy

In a survey carried out on 87 rotted fig fruits samples collected in the Apulia region of Italy, the authors isolated 126 Fusarium strains identified as F. ramigenum (69 strains), F. solani (49), F. proliferatum (five) and three not identified. Investigation on the fertility of the strains belonging to F. proliferatum and F. ramigenum revealed that only strains of F. proliferatum were fertile. The identity of F. ramigenum strains was confirmed by sequencing a portion of the translation elongation factor-1α gene. When Fusarium species were analysed for their toxigenicity, 37/69 strains of F. ramigenum produced fusaric acid (FA) up to 525 mg kg^?1; 30 strains produced beauvericin (BEA) up to 190 mg kg^?1; 60 strains produced fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) up to 1575 mg kg^?1 of total FBs; and two strains produced fusaproliferin (FUP) up to 345 mg kg^?1; all five strains of F. proliferatum produced FA at low levels; two strains produced BEA up to 205 mg kg^?1; one strain produced FB₁ and FB₂, 1100 and 470 mg kg^?1, respectively; and one strain produced FUP, 820 mg kg^?1; F. solani (30 strains) produced FA, 13 strains up to 215 mg kg^?1. Few fungal extracts showed high toxicity toward brine shrimp larvae and in some cases in relation to BEA and FA content. A pathogenic assay on fig fruits showed that all three species were pathogenic, with higher virulence of F. ramigenum. These data report for the first time the production of BEA and FB₁/FB₂ by F. ramigenum and show that it is a main agent of fig endosepsis in Apulia and can contribute to fumonisin contamination of fresh and dried figs.     

Fusariotoxins in asparagus – their biosynthesis and migration

Asparagus is often infected by fungi of the Fusarium genus, a causal agent of crown and root rot, which decreases the quantity and quality of spears. Fusarium oxysporum and Fusarium proliferatum are the most severe asparagus pathogens, well known as mycotoxin producers, mainly fumonisins and moniliformin. The present study was undertaken to estimate fumonisin B₁, moniliformin and ergosterol concentrations in asparagus tissue. Moreover, the possibility of toxin transport to the edible asparagus part during the inoculation by F. oxysporum and F. proliferatum of different plant parts (root, crown and stem base) and the potential risk for consumers were assessed. Our studies showed that the highest capability of producing fumonisin B₁ and moniliformin was demonstrated from isolates of F. proliferatum. The highest level of fumonisin B₁ in edible spears was detected when the asparagus crown was inoculated with F. oxysporum and F. proliferatum. The lowest concentration was found in the case of storage root inoculation, which corresponds with mycelium absence and the long distance from the roots to the stem. Similar results were demonstrated for moniliformin. The mycotoxin content was confirmed even in healthy spears (without disease symptoms and mycelium presence), which might indicate that the transport of mycotoxins is possible from the soil through the root system to the top part of the plants.     

Toxicity profile of commercially produced indigenous banana beer

Mycotoxins, together with endotoxins, represent important classes of naturally occurring contaminants in food products, posing significant health risks to consumers. The aim of this study is to investigate the occurrence of both Fusarium mycotoxins and endotoxins in commercially produced traditional banana beer. Two brands of commercially produced traditional banana beer were collected from a local retail market in Kigali, Rwanda. Beer samples were analysed for the presence of deoxynivalenol (DON), fumonisin B₁ and zearalenone (ZEA), using an enzyme-linked immuno-sorbent assay (ELISA) method. The quantification of bacterial endotoxin using Limulus amoeboecyte lysate (LAL) assay was also conducted. The contamination levels were 20 and 6.7?µg?kg^?1 for DON; 34 and 31.3?µg?kg^?1 for FB₁; 0.66 and 2.2?µg?kg^?1 for ZEA in brands A and B of the beers, respectively. Results indicate that the levels of Fusarium toxins and bacterial endotoxin reported in this study did not pose adverse human health effects as a result of drinking/consuming banana beer. However, exposure to low/sub-threshold doses or non-toxic levels of endotoxins magnifies the toxic effect of xenobiotic agents (e.g. fungal toxins) on liver and other target organs. Considering Fusarium toxins and/or endotoxin contamination levels in other agricultural commodities intended for human consumption, health risks might be high and the condition is aggravated when beer is contaminated by mixtures of the mycotoxins, as indicated in this study.     

Fumonisin contamination and fumonisin producing black Aspergilli in dried vine fruits of different origin

Aspergillus niger isolates are able to produce fumonisins in high quantities on agar media with a low water activity. Several agricultural products fit this criterion, including dried vine fruits, dates and figs. Data on the occurrence and role of this species in fumonisin contamination of agricultural products with high sugar content are needed to clarify the importance of A. niger in human health. The mycobiota and fumonisin contamination of various dried vine fruit samples collected from different countries were examined to clarify the role of black Aspergilli in fumonisin contamination of such products. All except two of the examined samples were contaminated with black Aspergilli. Species assignment of the isolates was carried out using sequence analysis of part of the calmodulin gene. The range of fumonisin isomers present in the raisin samples, and produced by A. niger isolates collected from dried vine fruits was also examined using reversed-phase high-performance liquid chromatography/electrospray ionization-ion trap mass spectrometry (RP-HPLC/ESI-ITMS). Among the 30 A. niger/A. awamori isolates identified, 20 were found to be able to produce fumonisins (average contamination: 5.16 mg/kg; range: 0.017-19.6 mg/kg). The average fumonisin content of the 7 dried vine fruit samples which were found to be contaminated by potential fumonisin producing black Aspergilli was 7.22 mg/kg (range: 4.55-35.49 mg/kg). The isolates produced several fumonisin isomers also present in the dried vine fruit samples, including fumonisins B_1-4, 3-epi-FB₃, 3-epi-FB₄, iso-FB₁, and two iso-FB_2,3 forms. Fumonisin B₁ was detected for the first time in A. niger cultures. Most of these isomers have previously only been identified in Fusarium species. Our data indicate that A. niger and A. awamori are responsible for fumonisin contamination of dried vine fruits worldwide. The observed levels of contamination are alarming and pose a new threat for food safety.     

Fusarium infection of maize and maize-based products and exposure of a rural population to fumonisin B1 in Limpopo Province,South Africa

Fusarium species (spp.) and fumonisin B₁ (FB₁) contaminations were monitored in maize and porridge consumed by a rural population of Limpopo Province, South Africa. Faecal samples were also analysed for FB₁ as a means of estimating the degree of dietary exposure to this mycotoxin. In total, 142 samples of maize (n?=?54), porridge (47) and faeces (41) were screened for Fusarium spp. using a serial dilution technique followed by DNA sequencing, while FB₁ was further screened and quantified by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), respectively. At least four species of Fusarium were identified, of which F. verticillioides was the most prevalent in all three sample types analysed. The contamination levels of FB₁ were significantly higher in 87% of maize sampled (range?=?101–53,863?µg?kg^?1) as compared with porridge (74% incidence rate; range?=?0.2–20?µg?kg^?1) and faecal samples (100% incidence rate; range?=?0.3–464?µg?kg^?1). Thus, it can be deduced that the level of human exposure to FB₁ via the consumption of maize was high as several samples contained levels exceeding 1000?µg?kg^?1, which was strongly supported by the levels found in faecal samples. Further data revealed that a high proportion of FB₁ is destroyed or removed by processing maize into porridge. As maize porridge is consumed as a staple, the low levels found provide a means to limit exposure to FB₁. Levels of FB₁ found in the faeces which were higher indicate that other foods contaminated with the toxin are also consumed.