RESUMO
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.
Assuntos
Fungos Mitospóricos/isolamento & purificação , Micotoxinas/análise , Zea mays/microbiologia , Aspergillus/isolamento & purificação , Brasil , Clima , Fusarium/isolamento & purificação , Penicillium/isolamento & purificaçãoRESUMO
Since animal intoxication related to corn-based feed is frequently observed in the State of Paraná, Brazil, natural contamination by fumonisins in 48 corn samples (39 from the State of Paraná, and 9 from the Brazilian tropical states, Mato Grosso do Sul and Goias) harvested in 1990-1991 was investigated, along with fungal flora. The total mould count ranged from 6.3 x 10(2) to 5.5 x 10(7) cfu/g, and Fusarium moniliforme and Aspergillus species belonging to section Flavi were detected in 41 and 33 samples, respectively. Regarding the samples from the State of Paraná, F. moniliforme was present in 33 samples at a count of 1.0 x 10(2) to 1.6 x 10(7) cfu/g and Aspergillus spp. in section Flavi in 27 samples at 1.0 x 10(2) to 1.0 x 10(6) cfu/g. HPLC analysis of fumonisins in the corn showed that fumonisins B1 (FB1) and B2 (FB2) were positive for 97.4% and 94.8% of samples respectively. All the corn from North Paraná was positive for fumonisins, with average FB1 levels of 4.79 micrograms/g and average FB2 levels of 3.95 micrograms/g: the Central-West region had average levels of 3.30 and 2.52 micrograms/g, and the Central-East had average of 3.25 and 2.34 micrograms/g, respectively. Except for one negative sample all the corn samples from the Central Region were positive for fumonisins, averaging FB1 levels being 5.45 micrograms/g and FB2 levels being 5.09 micrograms/g. Out of eight samples from the tropical state of Mato Grosso do Sul, F. moniliforme was detected in seven and Aspergillus spp. in section Flavi in five samples with average FB1 levels of 10.59 micrograms/g and average for FB2 levels of 10.31 micrograms/g. The samples from Goias were also contaminated with these two fungi, with the FB1 contamination being 5.83 and the FB2 contamination 3.62 micrograms/g.