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 Capao, Bonito and Ribeirao Preto, two regions of the State of Sao 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 Capao Bonito and in 49% of the samples from Ribeirao Preto. Examination of wind-dispersed fungi also revealed a high incidence of F verticillioides. Soil mycoflora analyses showed that Penicillium was the most prevalent genus, although F verticillioides was present in 55.5% of Capao, Bonito's samples and in 26.7% of Ribeirao 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 Capao Bonito's kernels were contaminated with fumonisin B-1 (FB1) (0.09-10.87 mug/g) and 53.8% with fumonisin B-2 (FB2) (0.05-0.52 mug/g); Ribeirao Preto's kernels presented contamination levels of 93.5% for FB1 (0.11-1 7.69 mug/g) and 61.3% for FB2 (0.05-5.24 mug/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.