## 4 Discussion  
Microbiological contamination of bee pollen arises from different sources. The primary sources of contamination of bee pollen by microscopic fungi are very difficult to control, and they can come from plants, from the digestive tract of bees or enter with dust from the air or soil. Possible sources of contamination may be the type of collector or the impurity of pollen traps [4; 19]. The botanical origin of the pollen is revealed by floral species, which varies depending on the climatic conditions during flowering and the region where the apiary is located [31]. In this study, the pollen of _Brassicaceae_ plants dominated, as bees collected the pollen from _Rosaceae Fabaceae_, _Paceae_ and _Asteraceae_ family plants. Some fungi can spread together with pollen [32]. Reports of fungi associated with pollen grains on plants are rare. The intricacy of the surface of many pollen grains could provide ample opportunities for the attachment of fungal spores [33]. During the flowering and pollination process, spores can germinate on female flower parts. The pollen from some _Asteraceae_ species is an optimal substrate for fungal growth due to its high lipid content [18]. The dominant endophytes such as _Alternaria_, _Cladosporium_ and _Epicocum_ seem not to be host-specific and are opportunistic colonizers of many plants [34]. According to researchers [35; 36], _Alternaria_, _Cladosporium_ and _Fusarium_ are some of the dominant mycobiota in fodder legumes. If bees visit these plants, the contaminated pollen grains will be transferred into the hives [3]. _Fusarium_ fungi producing trichothecenes were found in all species of leguminous grasses, the duration of vegetation of which is directly related to the amount of _Fusarium_ fungi, and with increasing duration increases the amount of _Fusarium_ fungi [37]. In the study, the moisture content of fresh bee pollen 5 h after collection was high (22.8%). Other researchers also obtained similar results: 14.6-37.7% [6], 21-30% [38] and  
Figure 2: Principal component analysis (PCA) for bee pollen stored for three days (DON—deoavilenol; ZEN—zeaalenone). 20% [39]. The moisture content of fresh bee pollen in this study varies slightly--between 0.01 and 0.02%--and was sufficient for fungi growth. The high moisture content can lead to an increase in microscopic fungal contamination which causes the production of mycotoxins [15; 40]. Fungi belonging to 14 genera were detected in the samples of fresh bee pollen. The highest number of colonies among fungi comprised _Alternaria_, _Cladosporium_ and Yeasts. Fungi of this genera are classified as saprotrophic field fungi derived from soil or plant residues [2]. Fungi of the genera _Alternaria_ and _Cladosporium_ are sufficiently resistant to the negative effects of the environment due to the accumulation of melanin [41], and their development and growth require high relative air humidity and low availability of food resources [2]. Studies conducted by [PERSON] et al. [16] have revealed that the amount of prevailing _Alternaria_ fungi in bee pollen comprised 86.6%. According to [PERSON] et al. [31], _Cladosporium_ in bee pollen was singled out as the second most common fungi. [PERSON] et al. [17] found that _Alternaria alternata_ and _Cladosporium cladosporoides_ were the most frequent isolates found in Slovakia bee pollen samples. Yeasts are not classified as microorganisms dangerous to human health, and they usually indicate the sanitary condition of hives and hygienic conditions during pollen collection and transportation [42]. Twelve analysed samples were contaminated with Yeasts, and their amount was abundant. The most abundant Yeasts were isolated in the pollen with the highest moisture content (22.8%). The abundance of Yeasts decreases rapidly in the first days of fresh pollen storage [43]. This is partly reflected by the data of our study.