Mycobiota and mycotoxins in freshly harvested and stored maize

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. [Projekat Ministarstva nauke Republike Srbije, br. TR-31023, br. TR-31033, br. TR-31053 i br. TR-31081]

Toxigenic fungal and mycotoxin contamination of maize samples from different districts in Serbia

“…Mycological analyses of maize grain samples were conducted according to the previously described methods by Krnjaja et al (2015). Based on morphological properties (colony and spore appearance), toxigenic species have been identified according to fungal keys of Burgess et al (1994) and Singh et al (1991).…”

Current and Future Technologies for Microbiological Decontamination of Cereal Grains

“…Krnjaja et al. () investigated mycobiota of maize—mycological analyses showed the presence of Aspergillus , Fusarium , and Penicillium on both freshly harvested and stored grains, however, the predominant species varied for each stage of processing. Similar observations were noted for maize—samples analyzed immediately after harvest showed predominance species of Alternaria , followed by species of Cladosporium and Penicillium , whereas after 120 days of storage the maize grains mycoflora consisted of various fungi belonging with predominance to Fusarium , Aspegillus and Penicillum genera (Dudoiu, Cristea, Lupu, Popa, & Oprea, ).…”

Natural toxigenic fungal and mycotoxin occurrence in maize hybrids

“…Nirenberg and F. proliferatum (Matsush.) Nirenberg have been detected on maize grains in Serbia (Jajić et al, 2008;Krnjaja et al, 2015;Obradović et al, 2018;Jakšić et al, 2019).…”