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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.

Kinetics of growth and fumonisin production by Fusarium moniliforme MRC 826 in corn "patty" cultures were investigated, and a technique was developed for the production of ["4C]fumonisin B1 ([14C]FB,) by using L-[methyl-'4CJmethionine as the precursor. A significant (P < 0.01) correlation exists between fungal growth and FB1 (r = 0.89) and FB2 (r = 0.87) production in corn patties, beginning after 2 days and reaching the stationary phase after 14 days of incubation. [14C]FB, was produced by adding L-[methyl-14CJmethionine daily to cultures during the logarithmic phase of production. Incorporation of the isotope occurred at C-21 and C-22 of the fumonisin molecule and was enhanced in the presence of unlabeled L-methionine. Although the concentration of exogenous unlabeled methionine is critical for incorporation of the 14C label, optimum incorporation was achieved by adding 50 mg of unlabeled L-methionine and 200 ,uCi of L-[methyl-14Cjmethionine to a corn patty (30 g) over a period of 9 days, yielding [14CJFB1 with a specific activity of 36 ,uCi/mmol.

In South Africa, child malnutrition is highly prevalent among children from in rural areas mostly at risk. In the Eastern Cape (EC) Province, maize is commonly used as complementary and weaning food. Previous studies conducted in parts of EC have indicated high levels of fumonisin B (FB) mycotoxins in home-grown maize, as well as the co-occurrence of other Fusarium mycotoxins, such as deoxynivalenol (DON) and zearalenone (ZEN). A cross-sectional study of children below 24 months was conducted in rural maize-subsistence farming areas in Centane, EC to determine mycotoxin exposure. Home-grown maize samples (n=171) were collected from households in the study area and analysed by LC-MS/MS for FB, DON and ZEN. Food intakes of 129 children were quantified using a validated quantitative food frequency questionnaire (QFFQ). Individual raw maize consumption was calculated using recipes from the QFFQ. Probable daily intakes (PDIs) for each mycotoxin were determined using a deterministic approach and were compared to the respective mycotoxins’ provisional maximum tolerable daily intake (PMTDI). The numerical means for total FB (sum of fumonisin B1, B2 and B3), DON and ZEN levels in home-grown maize were 1,035, 24.5 and 31.0 μg/kg, respectively. Mean daily maize intakes of children ranged from 2-321 g/day and increased with age. The mean PDIs for total FB, DON and ZEN were 8.4, 0.2 and 0.3 μg/kg body weight (bw)/day, respectively. Exposures stratified by age indicated persistent high mean PDIs for total FB, above the PMTDI of 2 μg/kg bw/day, ranging between 5.0-11.6 μg/kg bw/day. Mean exposure to DON and ZEN were below their relevant PMTDIs (1 and 0.5 μg/kg bw/day, respectively). Individually, 81 and 13% of children had exposures above the PMTDI for total FB and for ZEN, respectively. Results confirm the magnitude of FB exposure among vulnerable groups from rural maize subsistence farming areas in EC.

Fusarium globosum Rheeder, Marasas et Nelson is a recently described species originally isolated from corn kernels harvested in the Transkei region of South Africa. On the basis of morphological criteria, F. globosum is closely related to other common fungal contaminants of corn, viz. F. moniliforme, F. proliferatum, and F. subglutinans, and accordingly it has been classified in the section Liseola. Species within the section Liseola have been reported to produce either the fumonisin B or moniliformin (MON) mycotoxins and, in some cases both. Seventeen isolates of F. globosum, cultured on corn, were screened for the production of fumonisins B1 (FB1), B2 (FB2), B3 (FB3), and MON. All isolates produced FB1 (range 5−325 μg/g), while 15 of 17 also produced FB2 (range 1−4 μg/g). For 14 of 17 isolates, the levels of FB3 produced (range 4−24 μg/g) exceeded those of the corresponding FB2 concentrations. None of the isolates produced detectable levels of MON (<1 μg/g). In addition, several isolates of F. globosum also produced two additional fumonisin-like compounds, the mass spectral evidence of which suggests that they may be isomers of FB1 and FB2 or FB3, respectively. Keywords: Fumonisin B; Fusarium globosum; corn; maize; fungal contaminants; mycotoxins; carcinogens

Fusarium dimerum, typically a soil fungus, was isolated from an adult male suffering from a corneal ulcer following an injury to the eye. This fungus has not been described to cause human infections in South Africa and has not been recorded from soil, plant or organic material in this country. The macro- and microscopic characteristics of the isolate were found to be indistinguishable from described strains. Its authenticity was confirmed by comparing it to other human isolates from the eye obtained in the USA, thus rendering this the first report of F. dimerum from an eye infection in a human in South Africa.

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