Abstract
The incidence of mycobiota and mycotoxin levels were investigated in the freshly harvested maize kernel samples from October 2014 and in the samples of stored maize kernels from February 2015. Toxigenic fungal species (moulds) were isolated, cultivated and identified on agar plates according to standard mycological methods, while mycotoxins were detected by enzymelinked immuno-sorbent assay (ELISA). Mycological analyses of kernels showed the presence of toxigenic species from genera Aspergillus, Fusarium and Penicillium. Among the Aspergillus species, Aspergillus flavus was identified with higher incidence in the stored kernels (10.25%), than in freshly harvested kernels (3.67%) whereas A. parasiticus was the predominant species in the freshly harvested kernels (4.17%) compared to the stored kernels (0%). From the genus Fusarium three species were identified: F. graminearum, F. subglutinans and F. verticillioides, with the incidence of 1.08%, 8% and 25.75%, respectively in freshly harvested kernels and the incidence of 2.50%, 7.10% and 29.75%, respectively in the stored kernels. Species from genus Penicillium had higher incidence in freshly harvested kernels (14.25%) than in the stored kernels (9%). In addition, tested samples of harvested and stored maize kernels were 100% positive with aflatoxin B1 (AFB1), deoxynivalenol (DON) and total fumonisins B1, B2 and B3 (FBs). The mean levels of AFB1, DON and FBs were 2.77 ?g kg-1, 117.83 ?g kg-1, and 3700.84 ?g kg-1, respectively in the freshly harvested kernels and a mean levels of 2.16 ?g kg-1, 2034.40 ?g kg-1, and 5976.50 ?g kg-1, respectively in the stored maize kernels. In the freshly harvested maize kernel samples, statistically significant (P ? 0.05) positive correlations of kernel moisture content with the incidence of Penicillium spp. (r = 0.47), and levels of AFB1 (r = 0.46) and FBs (r = 0.47), and between the incidence of Penicillium spp. and level of AFB1 (r = 0.53) were established. In the stored maize kernel samples, statistically significant (P ? 0.05) positive correlations were found between the incidence of F. subglutinans and level of FBs (r = 0.50) and between levels AFB1 and FBs (r = 0.52). A highly significant (P ? 0.01) positive correlation was established between the incidence of F. verticillioides and level of FBs (r = 0.64) in freshly harvested maize kernel samples. These results indicate that the incidence of toxigenic fungi and levels of mycotoxins, in particular DON and FBs, were higher in the stored maize kernel samples than in freshly harvested maize kernels. Therefore, to prevent the development of toxigenic fungi and mycotoxins accumulation in post-harvest period it is necessary to thoroughly dry maize and keep it in hygienic food storages.
Highlights
Maize is cereal crop used for human and animal nutrition
(P ≤ 0.01) positive correlation was established between the incidence of F. verticillioides and level of FBs (r = 0.64) in freshly harvested maize kernel samples. These results indicate that the incidence of toxigenic fungi and levels of mycotoxins, in particular DON and FBs, were higher in the stored maize kernel samples than in freshly harvested maize kernels
The most important mycotoxins in maize kernels are aflatoxins produced by Aspergillus flavus and A. parasiticus
Summary
The contamination of maize with fungi (moulds) and their secondary metabolites (mycotoxins) represents a serious hazard to humans and animals. Climatic conditions and maize growing on large areas in Serbia are suitable for development of numerous toxigenic species, resulting with frequent animal feed contamination by toxic products of fungi – mycotoxins. Development of toxigenic fungi and bio-synthesis of mycotoxins most often depend on ample precipitation and low temperatures at the end of summer or beginning of autumn during sensitive phenophase of maize growing (Krnjaja et al, 2009). Production of farm animals, poultry and swine, in particular, requires a large amount of cereal grain. For this reason, most of the grain is stored until utilized. Storage conditions are determined by abiotic and biotic factors including microorganisms, insects, mites, rodents and birds (Santin et al, 2005)
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